Queue priorityQueue = new PriorityQueue<>();
PriorityQueue&<Integer, Integer>> pg = new PriorityQueue((a,b) -> a.getValue() - b.getValue());
PriorityQueue<int[]> queue = new PriorityQueue<int[]>(new Comparator<int[]> () {
public int compare(int[] m, int[] n) {
return m[1] - n[1];
}
});
Queue priorityQueueReverse = new PriorityQueue<>(verseOrder());
Queue priorityQueueReverse2 = new PriorityQueue<>((a, b) -> b-a);
Queue queue = new LinkedList<>();
queue.add(1);
Integer poll = queue.poll();
TreeMap<Integer, String> treeMap = new TreeMap<>();//从小到大Map.Entry<Integer, String> integerStringEntry = treeMap.pollFirstEntry();//从大到小Map.Entry<Integer, String> integerStringEntry1 = treeMap.pollLastEntry();Stack<Integer> stack = new Stack<>();
private static int simpleN(int i, int n) {int res = 1;int absN = Math.abs (n);while(absN > 0){res *= i;absN--;}return n > 0 ? res : 1 / res;
}
public static double powFast(double x, int n){double res = 1;long N = Math.abs(n);double target = x;while(N > 0){if((N & 1) == 1){res *= target;}target *= target;N = N >> 1;}return res;}
int[] datas = {1,10,5,4,6,8,2,7,3};
swap(datas, 5 ,2);
public static void swap(int[] datas, int i, int j){datas[i] = datas[i] ^ datas[j];datas[j] = datas[i] ^ datas[j];datas[i] = datas[i] ^ datas[j];
}public static void swap(int[] datas, int i, int j){datas[i] = datas[i] + datas[j];datas[j] = datas[i] - datas[j];datas[i] = datas[i] - datas[j];
}
/* * (1)斐波那契列 输入一个整数n，请输出斐波那契列的第n项* f(n) = f(n-1)+f(n-2), n > 1 n = 1 f(n) = 1 f(0) = 0* 0 1 1 2 3 5 8 13 21 34 55 89*/public static int getIndexRev(int n){if(n == 0){return 0;} else if(n == 1 || n == 2){return 1;} else {return getIndexRev(n - 1) + getIndexRev(n - 2);}}
public static void main(String[] args) {String[] words = {"ab", "cd", "de"};System.out.println(uniqueMorseRepeat(words));
}public static int uniqueMorseRepeat(String[] words){String[] codes = {".-","-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--.."};TreeSet<String> treeSet = new TreeSet<>();for (String word : words) {StringBuilder sb = new StringBuilder();for(int i = 0; i < word.length(); i++){sb.append(codes[word.charAt(i) - 'a']);}treeSet.String());}return treeSet.size();
}
import java.util.HashMap;public class LRUCache {static class Node{Node next;Node prev;int key;int val;public Node(){}public Node(int key, int val){this.key = key;this.val = val;}}HashMap<Integer, Node> map;Node head;Node tail;int capacity;int count;public LRUCache(int capacity){this.capacity = capacity;map = new HashMap<>();head = new Node();tail = new Node(); = tail;tail.prev = head;}public int get(int key){ainsKey(key)){Node node = (key);remove(node);insert(node);(key).val;}return -1;}public void insert(Node node){Node next = ; = = next;node.prev = head;next.prev = node;map.put(node.key, node);count++;if(count > capacity){remove(tail.prev);}}public void remove(Node node){if(count > 0){Node prev = node.prev;Node next = ; = next;next.prev = prev;node.prev = = ve(node.key);}}public void put(int key, int value){ainsKey(key)){Node node = (key);node.val = value;remove(node);insert(node);} else {Node node = new Node(key, value);insert(node);}}
}
int num = 12;
int sum = 0;
while(num > 0){if(num & 1 == 1){sum++;}num = num >> 1;
}
System.out.println(sum);
public double findMedian(){int n = data.size();//判断奇数偶数if((n & 1) == 1){(n / 2);} else {return ((n/2 -1) + (n / 2)) / 2.0;}
}
int[] nums = {1,2,2,1,3};int result = 0;for (int num : nums) {result ^= num;}System.out.println(nums);
//int[] ratings = new int[]{1,5,4,6,2,7,3}
//0-1表示索引0的孩子评分1，1-5表示索引1的孩子评分5，两个孩子评分高的分更糖果，一共最少分多少个
public static int candy(int[] ratings){if(ratings == null || ratings.length == 0){return 0;}int n = ratings.length;int[] d = new int[n];d[0] = 1;for(int i = 1; i < n; i++){if(ratings[i] > ratings[i - 1]){d[i] = d[i - 1] + 1;} else {d[i] = 1;}}int sum = d[n-1];for(int i = n -2; i >= 0; i--){if(ratings[i] > ratings[i + 1]){d[i] = Math.max(d[i], d[i + 1] + 1);}sum += d[i];}return sum;
}
public static int climstairsRecursive(int n){if(n < 2) return 1;return climstairsRecursive(n - 1) + climstairsRecursive(n - 2);
}public static int climstairsIterator(int n){int first = 1;int second = 2;for(int i = 1; i < n; i++){int third = first + second;first = second;second = third;}
}
public int maxWater(int[] height){int max = 0;int i = 0;int j = height.length - 1;while(i < j){int cur = Math.min(height[i], height[j]) * (j - i);max = Math.max(max, cur);if(height[i] < height[j]){++i;} else {j--;}}return max;}
public static void swap(int[] nums, int i, int j){int temp = nums[i];nums[i] = nums[j];nums[j] = nums[i];
}
public static int[] shuffer(int[] nums){for(int i = nums.length - 1; i > 0; i--){int j = Int(i + 1);swap(nums, i, j);}return nums;
}
空间：O(1)
时间：O(n ^ 2)
public static void sort(int[] nums){boolean hasChange = true;for(int i = 0; i < nums.length - 1; i++){hasChange = false;for(int j = 0; j < nums.length - 1 - i; j++){if(nums[j] > nums[i + 1]){swap(nums, j, j + 1);hasChange = true;}}}}
private static void doQuickSort(int[] datas, int low, int high){if(low < high){int priority = partition(datas, low, high);doQuickSort(datas, 0, priority);doQuickSort(datas, priority + 1, high);}}private static int partition(int[] datas, int low, int high) {int priority = datas[low];while(low < high) {while(low < high && datas[high] >= priority){high--;}datas[low] = datas[high];while(low < high && datas[low] <= priority) {low++;}datas[high] = datas[low];}datas[low] = priority;return low;}
空间：O(1)
时间：O(n ^ 2)
//从i开始，插入到它们前面
public static void insertSort(int[] nums){for(int i = 1; i < nums.length; i++) {if(nums[i] < nums[i - 1]){int temp = nums[i];int j = i - 1;for(; j >= 0 && nums[j] > temp; j--){nums[j + 1] = nums[j];}nums[j + 1] = temp;}}}
public static void selectSort(int[] nums){for(int i = 0; i < nums.length - 1; i++){int minIndex = i;for(int j = i + 1; j < nums.length; j++){if(nums[j] < nums[minIndex]){minIndex = j;}}if(minIndex != i){swap(nums, i, minIndex);}}}
public static void guibingSort(int[] nums){doGuiBingSort(nums, 0 , nums.length - 1);}public static void doGuiBingSort(int[] nums, int low, int high){if(low < high){int mid = low + (high - low) / 2;doGuiBingSort(nums, low, mid);doGuiBingSort(nums, mid + 1, high);merge(nums, low, mid, high);}}private static void merge(int[] nums, int low, int mid, int high) {int[] copy = nums.clone();int k = low, i = low, j = mid + 1;while(k <= high){if(i > mid){nums[k++] = copy[j++];} else if(j > high){nums[k++] = copy[i++];} else if(copy[j] < copy[i]){nums[k++] = copy[j++];} else {nums[k++] = copy[i++];}}}public static int doBinarySort(int[] nums, int target){if(nums == null){return -1;} else {int low = 0;int high = nums.length - 1;while(low <= high){int mid = low + (high - low) / 2;if(target < nums[mid]) {high = mid - 1;} else if(target > nums[mid]){low = mid + 1;} else {return mid;}}}return -1;} public static boolean check(int n) {if (n <= 0){return false;}while(n % 3 == 0){n /= 3;}return n == 1;} public static void main(String[] args) {int[] nums = {1,5,2,6,3,8,7,4,9};int[] twoSum = twoSum(nums, 11);}private static int[] twoSum(int[] nums, int target) {HashMap<Integer, Integer> hashMap = new HashMap();for(int i = 0; i < nums.length; i++){int num = target - nums[i];ainsKey(num)){return new int[]{(num).intValue(), i};}hashMap.put(nums[i], i);}return null;}public int[] getTwoNumSumToGivenValue(int[] numbers, int target){int i = 0, j = numbers.length - 1;while(i < j){if(numbers[i] + numbers[j] > target) --j;if(numbers[i] + numbers[j] < target) i++;else return newInt[]{i,j};}return newInt[]{-1, -1};
} public static List<Integer> data = new ArrayList<>();public void addNum(int num){int idx = data.size() - 1;while(idx >=0 && (idx) > num) {idx--;}data.add(idx + 1, num);}public double findMedian(){if((data.size() & 1) == 1){(data.size() / 2);} else {return (((data.size() / 2 - 1) + (data.size() / 2)) / 2.0);}}public int[] searchIn2DArray(int[][] matrix, int target){if(matrix == null || matrix.length == 0 || matrix[0] == null || matrix[0].length == 0|| target < matrix[0][0]|| target > matrix[matrix.length - 1][matrix[0].length - 1]){return new int[]{-1, -1};}int m = matrix.length;int n = matrix[0].length;int i = 0;int j = n - 1;while(i < m && j >= 0){if(matrix[i][j] > target){j--;} else if(matrix[i][j] < target){i++;} else {return new int[]{i, j};}}return new int[]{-1, -1};
} public void mergeTwoSortedArray(int[] nums1, int m, int[] nums2, int n){int i = m -1;int j = n - 1;int k = m + n -1;while(i >= 0 && j >= 0){if(nums2[j] > nums1[i]){nums1[k--] = nums2[j--];} else {nums1[k--] = nums1[i--];}}while(j >= 0){nums1[k--] = nums2[j--];}} public static int maxSubArr(int[] nums) {int max = Integer.MIN_VALUE;int cur = 0;for(int i = 0; i < nums.length; i++){cur = cur <= 0 ? nums[i] : (cur + nums[i]);max = Math.max(max, cur);}return max;}public static void move2ZerosAssign(int[] nums){if(nums == null || nums.length < 1){return ;}int cur =0;for(int fast = 0; fast < nums.length; fast++){if(nums[fast] != 0){nums[cur] = nums[fast];cur++;}}for(;cur < nums.length; cur++){nums[cur] = 0;}}public int uniquePathWithObstacles(int[][] grid){int m = grid.length;int n = grid[0].length;int[][] d = new int[m][n];d[0][0] = grid[0][0] == 1 ? 0 : 1;for(int i = 1; i < m; i++){d[i][0] = grid[i][0] == 1 ? 0 : 1;}for(int j = 1; j < n; j ++){d[0][j] = grid[j][0] == 1 ? 0 : 1;}for(int i = 1; i < m; i++){for(int j = 1; j < n; j++){d[i][j] = grid[i][j] == 1 ? 0 : d[i-1][j] + d[i][j-1];}}return d[m-1][n-1];}//给出一个每一层的消耗例如int[] cost = {1,2,3,4}
//爬到1层消耗1，爬到2层不管是从0-2还是1-2消耗都是2，这里最小消耗是4(1-3,3完了之后走2步就上完楼了)
public static int minCostClimbingStairs(int[] cost){if(cost == null || cost.length == 0){return 0;}if(cost.length == 1){return cost[0];}int n = cost.length;int[] d = new int[n];d[0] = cost[0];d[1] = cost[1];for(int i = 2; i < n; i++){d[i] = Math.min(d[i-1], d[i-2]) + cost[i];}return Math.min(d[n-2], d[n-1]);
} public static int geMax(int[] nums){Map<Integer, Integer> map = new HashMap<>();int maxNum = 0;int maxCount = 0;for(int i = 0; i < nums.length; i++){int newCnt = OrDefault(nums[i], 0) + 1;map.put(nums[i], newCnt);if(newCnt > maxCount){maxCount = newCnt;maxNum = nums[i];}}return maxCount;} //缺失的数字，数字从0到n连续排列，去除一个，放到数组中找出来public static int getInt(int[] nums){int n = nums.length;int result = 0;//(0,1,3)==> 0^0 1^1 2^3 ==>2^3^3==>2for(int i = 0; i < nums.length; i++){result = result ^ i ^ nums[i];}return result ^ n;} void permuteRec(List<Integer> nums, int start, List<List<Integer>> result){if(start == nums.size()){result.add(new ArrayList(nums));} else {for(int i = start; i < nums.size(); i++){Collections.swap(nums, i, start);permuteRec(nums, start + 1, result);Collections.swap(nums, i, start);}}}public List<List<Integer>> permute(int[] nums){if(nums == null || nums.length == 0){return new ArrayList<>();}List<List<Integer>> result = new ArrayList<>();List<Integer> list = new ArrayList<>();for (int num : nums) {list.add(num);}permuteRec(list, 0, result);return result;}public int[][] insertByMerge(int[][] intervals, int[] newInterval){int[][] temp = new int[intervals.length + 1][2];int size = 0;int p = 0;for(; p < intervals.length && intervals[p][0] < newInterval[0]; ++p){temp[size++] = intervals[p];}if(size == 0 || temp[size - 1][1] < newInterval[0]){temp[size++] = newInterval;} else {temp[size - 1][1] = Math.max(temp[size - 1][1], newInterval[1]);}for(;p < intervals.length; p++){if(temp[size - 1][1] < intervals[p][0]){temp[size++] = intervals[p];} else {temp[size - 1][1] = Math.max(temp[size - 1][1], intervals[p][1]);}}pyOf(temp, size);}public boolean isBst(){ArrayList<E> keys = new ArrayList();inOrder(root, keys):for(int i = 1; i < keys.size(); i++){(i - 1)(i)) > 0){return false;}}return true;
}public void inOrder(Node root, List keys){if(root == null){return;}inOrder(node.left, keys);keys.add(node.key);inOrder(node.right, keys);
}public boolean isSameTree(TreeNode p, TreeNode q) {if(p==null&&q==null) return true;if( (p==null&&q!=null)||(q==null&&p!=null) ) return false;if(p.val!=q.val) return false;return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}// 递归法public boolean isSymmetric2(TreeNode root) {return root==null || func(root.left, root.right);}public static boolean func(TreeNode left, TreeNode right){if(left==null || right==null)return left == right;return (left.val==right.val) && func(left.left,right.right) && func(left.right,right.left);}//非递归public static boolean isSymmetricTreeIterative(TreeNode root){if(root == null){return true;}Queue<TreeNode> queue = new LinkedList<>();queue.add(root.left);queue.add(root.right);while(!queue.isEmpty()){TreeNode left = queue.poll();TreeNode right = queue.poll();if(left == null && right == null){return true;} else if(left == null || right == null){return false;} else {if(left.val == right.val){return true;}queue.add(left.left);queue.add(right.right);queue.add(left.right);queue.add(right.left);}}return false;}public List<List<Integer>> levelOrder(TreeNode root) {Queue<TreeNode> qu = new LinkedList<>();List<List<Integer>> res = new ArrayList<>();if(root==null)return res;qu.add(root);while(!qu.isEmpty()){ //两个whileint size = qu.size();List<Integer> temp = new ArrayList<>();while(size>0){TreeNode tn = qu.remove();if(tn!=null) {if(tn.left!=null)qu.add(tn.left);if(tn.right!=null)qu.add(tn.right);}temp.add(tn.val);size--;}res.add(temp);}return res;}public int maxDepth(TreeNode root) {if(root==null) return 0;return Math.max(maxDepth(root.left),maxDepth(root.right)) + 1;
}
public int minDepth(TreeNode root) {if(root==null) return 0;return Math.min(minDepth(root.left),minDepth(root.right)) + 1;
}public static int getHeightAndCheck(TreeNode treeNode){if(treeNode == null) {return 0;}int left = getHeightAndCheck(treeNode.left);if(left == -1){return -1;}int right = getHeightAndCheck(treeNode.right);if(right == -1){return -1;}if(Math.abs(left - right) > 1) return -1;return Math.abs(left - right) + 1;}public static int maxDepthIterative(TreeNode treeNode){if(treeNode == null) return 0;Queue<TreeNode> q = new LinkedList()q.add(treeNode);int depth = 0;while(!q.isEmpty()){int size = q.size();for(int i = 0; i < size; i++){TreeNode poll = q.poll();if(poll.left != null){q.add(poll.left);} else if(poll.right != null){q.add(poll.right);}}++depth;}return depth;}public static TreeNode invertBinaryTreeIterative(TreeNode root){if(root == null) {return root;}Queue<TreeNode> q = new LinkedList<>();q.add(root);while(!q.isEmpty()){TreeNode poll = q.poll();TreeNode tmp = poll.left;poll.left = poll.right;poll.right = tmp;if(poll.left != null){q.add(poll.left);}if(poll.right != null){q.add(poll.right);}}return root;} public static int minDepth(TreeNode root){if(root == null){return 0;}if(root.left == null && root.right == null) {return 1;}if(root.left == null){return minDepth(root.right) + 1;}if(root.right == null){return minDepth(root.left) + 1;}return Math.min(minDepth(root.left), minDepth(root.right)) + 1;}public static void path(TreeNode root, int sum, List<Integer> elem, List<List<Integer>> result){if(root == null){return;}elem.add(root.val);if(root.left == null && root.right == null && root.val == sum){result.add(new ArrayList<>(elem));}path(root.left, sum - root.val, elem, result);path(root.right, sum - root.val, elem, result);ve(elem.size() - 1);
}public List<List<Integer>> pathSumRecursive(TreeNode root, int sum){List<List<Integer>> result = new ArrayList<>();List<Integer> elem = new ArrayList<>();path(root, sum, elem, result);return result;}public static boolean verify(int[] nums, int start, int end){if(start == end || start + 1 == end){return true;}int root = nums[start];int i = start + 1;while(i < end && nums[i] < root) {i++;}int mid = i ;while(i < end && nums[i] > root) {i++;}if(i == end){return verify(nums, start + 1, mid) && verify(nums, mid, end);} else {return false;}}public static boolean verifyPreOrder(int[] preOrder){if(preOrder == null){return false;}return verify(preOrder, 0, preOrder.length);}public TreeNode search(TreeNode root, int val){if(root == null || root.val == val){return val;}else if(root.val > val){return search(root.left, val);} else {return search(root.right, val);}
}private static List<String> concat(String str){List<String> list = new ArrayList();Stack<Character> stack = new Stack<>();if(str == null || str.length() < 1){return null;}CharArray(), str.length(), 0, stack, list);return list;}private static void toConcat(char[] chars, int count, int cur, Stack<Character> stack, List<String> list) {if(cur == count){StringBuilder sb = new StringBuilder();Iterator<Character> iterator = stack.iterator();while(iterator.hasNext()) {sb.());}list.String());return;}for(int i = 0; i < count; i++){ains(chars[i])){continue;}stack.push(chars[i]);toConcat(chars, count, cur + 1, stack, list);stack.pop();}}String s = "()[]{}";
System.out.println(isValid(s));
public static boolean isValid(String s){Stack<Character> stack = new Stack();for(int i = 0; i < s.length(); i++){char c = s.charAt(i);if(c == '(' || c == '[' || c =='{'){stack.push(c);} else {if(stack.isEmpty()){return false;}Character pop = stack.pop();if(c == ')' && pop !='('){return false;}if(c == ']' && pop != '['){return false;}if(c == '}' && pop != '{'){return false;}}}return true;
}public class MinStack{Stack<Integer> stack;Stack<Integer> minStack;public MinStack(){stack = new Stack();minStack = new MinStack();}public void push(int x){stack.push(x);if(minStack.isEmpty() || x < minStack().peek()){minStack.push(x);} else {minStack.push(minStack.peek());}}public void pop(){stack.pop();minStack.pop();}public int top(){return minStack.peek();}public int getMin(){return minStack.peek();}
} private Stack<Integer> stack = new Stack();private Stack<Integer> minStack = new Stack<>();public void push(int x){stack.push(x);if(minStack.isEmpty() || minStack.peek() < x){minStack.push(x);}}public void pop(){if(stack.peek() == minStack.peek()){minStack.pop();}stack.pop();}public int top(){stack.peek();}public void getMin(){minStack.peek();}public class StackQueue<E> {private Stack<E> in = new Stack();private Stack<E> out = new Stack();private void transferIfEmpty(){if(out.isEmpty()) {while(!in.isEmpty()){out.push(in.pop());}}}public void push(E e){in.push(e);}public E pop(){transferIfEmpty();return out.pop();}public E peek(){transferIfEmpty();return out.peek();}public boolean empty(){return in.isEmpty() && out.isEmpty();}
}public static boolean isPalindromeUsingStack(ListNode<Integer> listNode){Stack<Integer> stack = new java.util.Stack();for(ListNode<Integer> p = listNode; p != null; p = p.next){stack.push(p.val);}for(ListNode p = listNode; p != null; p = p.next){if(p.val != stack.pop()){return false;}}return true;}public ListNode mergeTwoSortedList(ListNode<Integer> l1, ListNode<Integer> l2){ListNode dummy = new ListNode(0);ListNode p = dummy;while(l1 != null && l2 != null){if(l1.val < l2.val){//1->2 p->1 l1 = 2p.next = l1;l1 = l1.next;} else {p.next = l2;l2 = l2.next;}p = p.next;}if(l1 != null) {p.next = l1;}if(l2 != null){p.next = l2;};}public ListNode<Integer> oddEventList(ListNode head){if(head == null || == null || == null){return head;}ListNode eventHead = ;ListNode odd = head;ListNode even = eventHead;while(even != null && != null){ = ;odd = ; = ;even = ;} = eventHead;return head;}public ListNode<Integer> reverseList(ListNode head){ListNode cur = head;ListNode pre = null;while(cur != null){ListNode next = ; = pre;pre = cur;cur = next;}return pre;
} PriorityQueue<Integer> minHeap = new PriorityQueue<>(k, new Comparator<Integer>() {@Overridepublic int compare(Integer o1, Integer o2) {//从小到打排序return o1 - o2;}});for(int i = 0; i < nums.length; i++){minHeap.add(nums[i]);}for(int i = 0; i < k - 1; i++){minHeap.poll();}return minHeap.poll();
//===================================================================
public int findKth(int[] nums, int k){Queue<Integer> minHeap = new PriorityQueue<>();for(int num: nums){if(minHeap.size() < k){minHeap.add(num);} else if(num > minHeap.peek()) {minHeap.poll();minHeap.add(num);}}return minHeap.peak();
} private static Queue<Integer> minHeap = new PriorityQueue();private static Queue<Integer> maxHeap = new verseOrder());public void addNum(int num){minHeap.add(num);maxHeap.add(minHeap.poll());if(maxHeap.size() - minHeap.size() > 1){minHeap.add(maxHeap.poll());}}public double findMedian(){if(maxHeap.size() > minHeap.size()){return maxHeap.peek();} else {return (maxHeap.peek() + minHeap.peek()) / 2.0;}}public static void main(String[] args) {int[] datas = {6,2,4,8,7,10,1,3,9};doQuickSort(datas, 0, datas.length - 1);System.out.JSONString(datas));}private static void doQuickSort(int[] datas, int low, int high){if(low < high){int priority = partition(datas, low, high);doQuickSort(datas, 0, priority);doQuickSort(datas, priority + 1, high);}}private static int partition(int[] datas, int low, int high) {int priority = datas[low];while(low < high) {while(low < high && datas[high] >= priority){high--;}datas[low] = datas[high];while(low < high && datas[low] <= priority) {low++;}datas[high] = datas[low];}datas[low] = priority;return low;}f(n) = f(n-1) + f(n-2)
f(1) = 1 f(2) = 2 f(3) = 3 f(4)=5
public int climbStairs(int n){if(n <= 3){return n;}return climbStairs(n - 1) + climbStairs(n - 2);
}int[] steps = new int[n+1];
steps[1] = 1
steps[2] = 2
for(int i = 3; i <= n; i++){steps[i] = steps[i - 1] + steps[i - 2];
}
return steps[n];int[] steps = new int[3];
steps[0] = 1
steps[1] = 2
for(int i = 2; i < n; i++){steps[i % 3] = steps[(i - 1) % 3] + steps[(i - 2) % 3];
}
return steps[(n - 1) % 3];从迷宫一端走到另一端的走法
public int unquePaths(int m, int n){if(m == 0 || n == 0){return 1;}int[][] path = new int[m][n];for(int i = 0; i < m; i++){path[i][0] = 1;}for(int j = 0; j < n; j++){path[0][j] = 1;}for(int i = 1; i < m; i++){for(int j = 1; j < n; j++){path[i][j] = path[i - 1][j] = path[i][j-1];}}return path[m - 1][n - 1];
}public static String reverseWordAndChar(String s){if(s == null || s.length() == 0){return s;} else {String[] splitCharArr = s.split(" ");StringBuilder sb = new StringBuilder();for(int i = splitCharArr.length - 1; i >= 0; i--){sb.append(reverseStr(splitCharArr[i]) + " ");}String().trim();}}public static String reverseWord(String s){if(s == null || s.length() == 0){return s;} else {String[] splitCharArr = s.split(" ");StringBuilder sb = new StringBuilder();for(int i = splitCharArr.length - 1; i >= 0; i--){sb.append(splitCharArr[i] + " ");}String().trim();}}public static String reverseStr(String s){StringBuilder sb = new StringBuilder();for(int i = s.length() - 1; i >= 0; i--){sb.append(s.charAt(i));}String();} public static void main(String[] args) {String a = "1101";String b = "110";StringBuilder sb = new StringBuilder();int i = a.length() - 1;int j = b.length() - 1;int carry = 0;while( i >= 0 || j >= 0 || carry != 0){int sum = carry;if(j >= 0) {sum += a.charAt(i--) - '0';}if(j >= 0) {sum += b.charAt(j--) - '0';}
// sb.append(sum % 2);sb.append(sum & 1);
// carry = sum / 2;carry = sum >> 1;}System.out.verse().toString());}public static void count(String s, List<List<Integer>> res) {if (s == null || s.length() == 0) {return;}int n = s.length();int count = 0;boolean[][] visited = new boolean[n][n];for (int i = n - 1; i >= 0; i--) {for (int j = i; j < n; j++) {if (i == j) {visited[i][j] = true;} else if (i + 1 == j) {visited[i][j] = (s.charAt(i) == s.charAt(j));} else {visited[i][j] = (s.charAt(i) == s.charAt(j) && visited[i + 1][j - 1]);}if (visited[i][j]) {count++;List list = new ArrayList();list.add(i);list.add(j);res.add(list);}}}}public int countSubstrings(String s) {// 动态规划法boolean[][] dp = new boolean[s.length()][s.length()];int ans = 0;ArrayList list = new ArrayList();for (int j = 0; j < s.length(); j++) {for (int i = 0; i <= j; i++) {if (s.charAt(i) == s.charAt(j) && (j - i < 2 || dp[i + 1][j - 1])) {dp[i][j] = true;list.add(s.subString(i, j+1);ans++;}}}list.sort((s1, s2) -> {return s1.length() - s2.length();})return ans;
}public static int strContainsStr(String s1,String s2){if(s1 != null && s2 != null){int j = 0;for (int i = 0; i < s1.length () - s2.length () + 1; i++){for(j = 0; j < s2.length (); j++){if(i+j < s1.length ()){if(s1.charAt (i+j) != s2.charAt (j)){break;}}}if(j == s2.length ()){return 1;}}}return -1;} public static int contains(String s1, String s2){if(s1 == null || s2 == null || s1.length() == 0 || s2.length() == 0){return -1;}//abcd ab 最多遍历到2 4-2=2for(int i = 0; i <= s1.length() - s2.length(); i++){int j = 0;int k = i;for(; j < s2.length() && k < s1.length() && s1.charAt(k) == s2.charAt(j); j++, k++){if(j == s2.length() - 1){return i;}}}return -1;}public static boolean isPalindromeString(int x){String str = String.valueOf(x);int i = 0;int j = str.length();while(i < j){if(str.charAt(i) != str.charAt(j)){return false;}i++;j--;}return true;}本文发布于:2024-01-28 06:10:59，感谢您对本站的认可！
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