C. Exponential notation

C. Exponential notation

这个题典型的模拟题，各种情况要考虑:

1.为0的情况

       1)0

       2)00

       3)0.0

2.没有小数点的情况

      1)16

      2)100

      3)001

      4) 1

3.带小数点的情况

     1)100.

     2)100.00

     3)01.00

     4)1.010

     5)12.1

     6)00.0010

各种考虑，最后A掉，上代码吧

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>using namespace std;const int MAX = 1000010;char s[MAX];int main(){while (scanf("%s", s) != EOF){int len = strlen(s);int pre = 0, end = len-1;while (pre<len && s[pre]=='0' && s[pre]!='.'){    //除去首部的0pre++;}while (end >=0 && s[end] == '0' && s[end] != '.'){ //除去末尾的0end--;}int mark = 0;for (int i = 0; i<len; i++) if (s[i] == '.'){  //判断是否具有小数点  mark = 1;break;}if (mark == 0){      //如果不带小数点，末尾的0不能除去end = len-1;}if (pre == end){            //值为个位数if (s[pre] == '.'){printf("0n");}else{printf("%cn",s[pre]);}continue;}if (pre > end){     //为0的一种情况 "0, 00"printf("0n");continue;}int u = pre;int e = 0, sign;      //确定指数if (s[pre] != '.'){         //若指数应该为正sign = 1;while (pre<=end && s[pre] != '.'){e++;pre++;}e--;}else{                      //若指数应该为负sign = -1;pre++;e++;while (s[pre] == '0'){pre++;e++;}}if (s[end] == '.' || mark==0){   //当小数位为0或者不存在的时候,确定整数的最后一个非0数字，考虑到类似100 100. 100.00while (s[end] == '0' || s[end]=='.'){end--;}}//输出结果if (sign > 0){printf("%c", s[u]);if (u != end){printf(".");for (int i = u+1; i<=end; i++) if (s[i] != '.'){printf("%c",s[i]);}}if (e > 0){printf("E%d",e);}printf("n");}else{printf("%c", s[pre]);if (pre != end){printf(".");for (int i = pre+1; i<=end; i++) {printf("%c", s[i]);}}if (e > 0){printf("E%d", -1*e);}printf("n");}}return 0;
}