扩展kmp模板

#include <iostream>
#include <cstring>
using namespace std;
const int N = 101010;
int Next[N],extand[N];
void getNext(char *T){// Next[i]: 以第i位置开始的子串 与 T的公共前缀
    int i,length = (int)strlen(T);
    Next[0] = length;
    for(i = 0;i<length-1 && T[i]==T[i+1]; i++);
    Next[1] = i;
    int a = 1;
    for(int k = 2; k < length; k++){
        int p = a+Next[a]-1, L = Next[k-a];
        if( (k-1)+L >= p ){
            int j = (p-k+1)>0? (p-k+1) : 0;
            while(k+j<length && T[k+j]==T[j]) j++;// 枚举(p+1，length) 与(p-k+1,length) 区间比较
            Next[k] = j, a = k;
        }
        else Next[k] = L;
    }
}
void getextand(char *S,char *T){
    memset(Next,0,sizeof(Next));
    getNext(T);
    int Slen = (int)strlen(S), Tlen = (int) strlen(T), a = 0;
    int MinLen = Slen>Tlen?Tlen:Slen;
    while(a<MinLen && S[a]==T[a])
        a++;
    extand[0] = a, a = 0;
    for(int k = 1; k < Slen; k++){
        int p = a+extand[a]-1, L = Next[k-a];
        if( (k-1)+L >= p ){
            int j = (p-k+1)>0? (p-k+1) : 0;
            while(k+j<Slen && j<Tlen && S[k+j]==T[j] ) j++;
            extand[k] = j;a = k;
        }
        else extand[k] = L;
    }
}

int main(){
    char s[N],t[N];
    while(~scanf("%s %s",s,t)){
        getextand(s,t);
        for(int i = 0; i < strlen(t); i++)
            printf("i=%d next[i]=%d\n",i,Next[i]);
        puts("");
        for(int i = 0; i < strlen(s); i++)
            printf("i=%d extend[i]=%d\n",i,extand[i]);
        puts("");
    }
}