wenbao与扩展kmp

给定两个字符串S和T（长度分别为n和m），下标从0开始，定义extend[i]等于S[i]...S[n-1]与T的最长公共前缀的长度，求出所有的extend[i]

next[i]： T[i]...T[m-1]与T的最长公共前缀长度；
extend[i]： S[i]...S[n-1]与T的最长公共前缀的长度。

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//C/C++ 模板
#include <iostream>
#include <stdio.h>
#include <string.h>
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 = strlen(T);
    next[0] = length;
    for(i = 0;i<length-1 && T[i]==T[i+1]; i++); //单独处理next[1]
    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 = strlen(S), Tlen = 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("%d ",next[i]);
        puts(""); 
        for(int i = 0; i < strlen(s); i++) printf("%d ",extand[i]);
        puts("");
    } 
}

/*
abababab abab
aaaabaaa aaaa
*/

 

 

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