"String Hash" "Bkdrhash" "Rabin-karp algorithm" template

#include <cstdio> #include <iostream> #include <cstring> #include <string> #include <set> using namespace std; #define MAXN 100001typedef unsigned long long ull;const ull seed=31;ull Seeds[maxn];char s[maxn],s2[ma Xn];int poss[maxn];//Violent string comparison bool Strcmp (const char a[],const int &l1,const int &r1,const char b[],const int &l 2,const int &r2) {for (int i=l1,j=l2;i<r1;++i,++j) if (A[i]!=b[j]) return 0;return 1;}  Natural overflow, L first pointer, R tail pointer, left closed right open ull bkdrhash (const char str[],const int &l,const int &r) {ull res=0;for (int i=l;i<r;++i) Res=res*seed+str[i];return Res;} Preprocessing to facilitate the transfer of hash (S[i...i+m-1] and hash (s[i+1...i+m]) void Init_seeds () {seeds[0]=1;for (int i=1;i<maxn;++i) seeds[i] =seeds[i-1]*seed;} Text string lookup, s text string, sub substring int rabinkarp (const char s[],const char sub[]) {int N=strlen (s), M=strlen (sub), Ull hsub=bkdrhash (Sub,    0,M), Hs=bkdrhash (S,0,m), for (int i=0;i<=n-m;++i) {if (hs==hsub && Strcmp (s,i,i+m,sub,0,m)) return i; Hs= (Hs-s[i]*seeds[m-1]) *seed+S[I+M];//O (1) transfer}return-1;}  int main () {init_seeds (); while (1) {scanf ("%s%s", S,S2);  printf ("%d\n", Rabinkarp (S,S2)); }return 0;}

String hash, Bkdrhash, Rabin-karp algorithm template