C - Perform the Combo

C - Perform the Combo

思路：当读到这个题的时候，第一反应就是枚举，但是，无线超时，没办法，那就变，利用前缀和，减少时间。

代码：

#include<iostream>
#include<string>
#include<algorithm>
#define MAX 200005
using namespace std;
long long str[MAX];
long long b[28];
char s[MAX];

int main(){
    int t,n, m;
    scanf("%d", &t);
    while (t--){
        memset(str, 0, sizeof str);
        memset(b, 0, sizeof b);
        scanf("%d%d", &n, &m);
        scanf("%s", s + 1);
        for (int i = 1; i <= m; ++i){
            long long a;
            scanf("%lld", &a);
            str[a] ++;
        }
        for (int i = n - 1; i >= 1; i--)
            str[i] += str[i + 1];
        for (int i = 1; i <= n; ++i){
            b[s[i] - 'a'] += str[i] + 1;
        }
        for (int i = 0; i < 26; ++i) {
            printf("%lld ", b[i]);
        }
        printf("\n");
    }
    return 0;
}