牛客：送外卖

牛客：送外卖

代码：

#include <bits/stdc++.h>
#define gcd __gcd
#define endl 'n'
using namespace std;
typedef long long ll;
typedef long double ld;
const ll maxn = 2e5+5;
const int inf=0x7fffffff;
int n,f=0;
int a[maxn];
int b[maxn];
int vis[maxn],vis1[maxn],in[maxn];
char ans[maxn];
int dfs(int pos,int step)
{if(pos<0||pos>n-1) return 0;if(pos==n-1){ans[step]=0;f=1;return 1;}if(vis[pos]){in[pos]=1;return 0;}vis[pos]=1;ans[step]='a';if(dfs(pos+a[pos],step+1)){if(in[pos]==1)f=2;return 1;}ans[step]='b';if(dfs(pos+b[pos],step+1)){if(in[pos]==1)f=2;return 1;}return 0;
}
int main()
{cin>>n;for(int i=0;i<n;i++){cin>>a[i];}for(int i=0;i<n;i++){cin>>b[i];}dfs(0,0);if(f==0) cout<<"No solution!"<<endl;else if(f==1) cout<<ans<<endl;else cout<<"Infinity!"<<endl;
}