PAT 1093. Count PAT's (25)

题目地址： http://www.patest.cn/contests/pat-a-practise/1093

水题

 1 #include<cstdio>

 2 #include<cstring>

 3 #include<iostream>

 4 

 5 using namespace std;

 6 

 7 const int MAXN = 100000 + 5;

 8 const int MOD = 1000000007;

 9 int d[MAXN][3];

10 

11 char str[MAXN];

12 

13 int solve(char *s) {

14         int ans = 0;

15         memset(d, 0, sizeof(d));

16         int len = strlen(s);

17         if (s[0] == 'P') ++d[0][0];

18         for (int i = 1; i < len; ++i) {

19                 d[i][0] = d[i - 1][0];

20                 d[i][1] = d[i - 1][1];

21                 if (s[i] == 'P') {

22                         ++d[i][0];

23                 } else if (s[i] == 'A') {

24                         d[i][1] += d[i][0];

25                 } else if (s[i] == 'T') {

26                         d[i][2] += d[i][1];

27                         ans += d[i][2];

28                         ans %= MOD;

29                 }

30         }

31         return ans;

32 }

33         

34 int main() {

35         while(cin >> str) {

36                 cout << solve(str) << endl;

37         }

38         return 0;

39 }