IOI06 The Deciphering of Mayan Writing

dmaya.cpp

//http://www.spoj.com/OI/problems/DMAYA/
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>

using namespace std;

int main () {
   int g, sz;
   char W[3001], S[3000001];
   scanf("%d %d\n", &g, &sz);
   scanf("%s %s\n", W, S);
   int buw[128],bus[128];
   memset(buw,(0),sizeof(buw));
   memset(bus,(0),sizeof(bus));
   for(int i = 0; i < g; i++)
      buw[W[i]-'0']++;
   queue<char> q;
   int count = 0;
   char c;
   for(int i = 0; i < sz; i++) {
      q.push(S[i]);
      ++bus[S[i]-'0'];
      while(bus[S[i]-'0'] > buw[S[i]-'0']) {
         c = q.front();
         q.pop();
         --bus[c-'0'];
      }
      if(q.size() == g) count++;
   }
   printf("%d\n", count);
   return 0;
}