http://codeforces.com/contest/1311/problem/C
給定一個長度爲 n 小寫字母字符串 s
給定一個長度爲 m 的數列 pi
對於每一個 pi，表示你要統計 s1~spi所對應的字母各一次。
最終，你還要統計整個字符串的字母各一次。
你需要求出 2626 2626 個小寫字母中每個字母被統計過的次數。
差分思想
#include <iostream>
#include <algorithm>
#include <cmath>
#include <ctype.h>
#include <cstring>
#include <cstdio>
#include <set>
#include <iostream>
#include <cstdio>
#include <fstream>
#include <algorithm>
#include <cmath>
#include <deque>
#include <vector>
#include <queue>
#include <string>
#include <cstring>
#include <map>
#include <stack>
#include <set>
#include<iomanip>
#define SIS std::ios::sync_with_stdio(false)
#define ll long long
#define INF 0x3f3f3f3f
const int mod = 1e9 + 7;
const double esp = 1e-5;
const double PI = 3.141592653589793238462643383279;
using namespace std;
const int N = 1e7 + 5;
const int maxn = 1 << 20;
ll powmod(ll a, ll b) { ll res = 1; a %= mod; while (b >= 0); for (; b; b >>= 1) { if (b & 1)res = res * a % mod; a = a * a % mod; }return res; }
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
/*void chafen(int l, int r, int k) {//差分函數
p[l] += k;
p[r + 1] -= k;
}*/
/*************************************************************/
int n, m;
int a[200010], b[200010];
int c[200010], d[200010];
int fk[30];
void insert(int l, int r, int p)
{
b[l] += p;
b[r + 1] -= p;
}
int main()
{
SIS;
int t;
cin >> t;
while (t--)
{
memset(b, 0, sizeof(b));
memset(c, 0, sizeof(c));
memset(fk, 0, sizeof(fk));
memset(a, 0, sizeof(a));
string s;
cin >> n >> m;
cin >> s;
for (int i = 1; i <= m; i++)
cin >> c[i];
c[m + 1] = n;
for (int i = 1; i <= n; i++)
{
insert(i, i, a[i]);
}
for (int i = 1; i <= m+1; i++)
{
insert(1, c[i], 1);
}
for (int i = 1; i <= n; i++) b[i] += b[i - 1];
for (int i = 1; i <= n; i++)
{
fk[s[i - 1] - 'a'] += b[i];
}
for (int i = 0; i < 26; i++)
cout << fk[i] << ' ';
cout << endl;
}
return 0;
}