Codeforces 113B Petr # string hash

Codeforces 113B Petr # string hash

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#include 
 
  #include #include 
  
   #include 
   
    using namespace std;typedef unsigned long long ll;const int key = 1e9 + 7;const int N = 2000 + 2;ll xp[N], h[N];char a[N], b[N], c[N];int la, lb, lc;vector
    
      posl;vector
     
       H;ll Hash(int s, int len) {return h[s] - h[s + len] * xp[len];}void make(char* s, ll* h, int len) {xp[0] = 1;for (int i = 1; i < N; ++i)xp[i] = xp[i - 1] * key;h[len] = 0;for (int i = len - 1; i >= 0; --i)h[i] = h[i + 1] * key + s[i];}int main() {ll hb = 0, hc = 0;scanf("%s%s%s", a, b, c);la = strlen(a);lb = strlen(b);lc = strlen(c);for (int i = lb - 1; i >= 0; --i)hb = hb * key + b[i];for (int i = lc - 1; i >= 0; --i)hc = hc * key + c[i];make(a, h, la);for (int i = 0; i + lc <= la; ++i) if (Hash(i, lc) == hc)posl.push_back(i);for (int i = 0; i + lb <= la; ++i)if (Hash(i, lb) == hb) {for (int j = 0; j < posl.size(); ++j) {if (posl[j] < i || posl[j] + lc < i + lb)continue;H.push_back(Hash(i, posl[j] + lc - i));}}sort(H.begin(), H.end());int ans = 0;if (H.size() > 0)ans = 1;for (int i = 1; i < H.size(); ++i)if (H[i] != H[i - 1])++ ans;printf("%d\n", ans); return 0;}