HDU 482 String

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #include <map>
14 #define LL long long
15 #define ULL unsigned long long
16 #define pii pair<int,int>
17 #define INF 0x3f3f3f3f
18 #define seek 131
19 using namespace std;
20 const int maxn = 100100;
21 map<ULL,int>mp;
22 char str[maxn];
23 ULL base[maxn],hs[maxn];
24 int main() {
25     int M,L,len,i,j,ans;
26     ULL tmp;
27     base[0] = 1;
28     for(i = 1; i < maxn; i++) base[i] = base[i-1]*seek;
29     while(~scanf("%d%d%s",&M,&L,str)){
30         len = strlen(str);
31         ans = 0;
32         hs[len] = 0;
33         for(i = len-1; i >= 0; i--)
34             hs[i] = hs[i+1]*seek+str[i]-‘a‘;
35         for(i = 0; i < L && i + M*L <= len; i++){
36             mp.clear();
37             for(j = i; j < i+M*L; j += L){
38                 tmp = hs[j] - hs[j+L]*base[L];
39                 mp[tmp]++;
40             }
41             if(mp.size() == M) ans++;
42             for(j = i+M*L; j+L <= len; j += L){
43                 tmp = hs[j-M*L] - hs[j-M*L+L]*base[L];
44                 mp[tmp]--;
45                 if(!mp[tmp]) mp.erase(tmp);
46                 tmp = hs[j] - hs[j+L]*base[L];
47                 mp[tmp]++;
48                 if(mp.size() == M) ans++;
49             }
50         }
51         printf("%d\n",ans);
52     }
53     return 0;
54 }