Description CA loves “6” very much. Now CA has a string S which consists of N digits. Now, she wonders that there are how many non-empty strings are substring of S and only contain number “6”. Input First line contains T denoting the number of testcases. T testcases follow. Each testcase contains a integer in the first line, denoting N, the length of string S. The second line is a string whose length is N. 1≤T≤10, 2≤N≤200000 Output For each test case, output answer. Sample Input 2 3 616 3 166
Sample Output 2 3
讲真这种题真不应该写个博客，但是重点就是没有想到用int 类型计算得到long long的过程中可能会爆炸，是我太菜了，发个博记录下。
#include<bits/stdc++.h> #define input freopen("input.txt","r",stdin) using namespace std; int main(){ //freopen("input.txt","r",stdin); int n,i,j,t,start,end,flag; long long sum; string s; scanf("%d",&t); while(t--){ sum=0; scanf("%d",&n); cin>>s; s+='0'; start=end=0; for(flag=0,i=0;i<=n;i++){ if(flag==0&&s[i]=='6'){ flag=1; start=i; } else if(flag==1&&s[i]!='6'){ flag=0; sum+=(long long)((1+(long long)(i-start))*(i-start)/2); //就是这！ } } cout<<sum<<endl; } return 0; }