ZOJ 3171 The Hidden 7's DP

传送门：http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=3203

题目大意给定一串字符串，需要计算出seven的个数。

#include<cstdio>#include<cstring>#include<string.h>const int MAXN=10000+10;char s[MAXN];const char seven[]=" seven";int main(){while(~scanf("%s",s)){long long dp[6]={1,0,0,0,0,0};int len=strlen(s);for(int i=0;i<len;i++){ if (s[i]>='A' && s[i]<='Z')              {                  s[i]+='a'-'A';              }  for(int j=5;j>=1;j--){if(seven[j]==s[i]){dp[j]+=dp[j-1];}}}printf("%lld\n",dp[5]);}}