51nod 1304 字符串的相似度（exkmp）

拓展kmp裸题

自己跟自己匹配即可

模板测试=v=

#include <iostream>
#include <cstring>
using namespace std;
const int maxn = 1e6 + ;
char S[maxn];
int Next[maxn], extend[maxn];
void GetNext(char *T, int *Next){
    int len = strlen(T);
    Next[] = len;
    int a, p;
    for(int i = , j = -; i < len; i++, j--){
       if(j <  || i + Next[i-a] >= p){
            if(j < ) p = i, j = ;
            while(p < len && T[p] == T[j])
                p++, j++;
            Next[i] = j;
            a = i;
       } else Next[i] = Next[i-a];
    }
}
void GetExtend(char *S, char *T, int *extend, int *Next){
    GetNext(T, Next);
    int a, p;
    int slen = strlen(S), tlen = strlen(T);
    for(int i = , j = -; i < slen; i++, j--){
        if(j <  || i + Next[i-a] >= p){
            if(j < ) p = i, j = ;
            while(p < slen && j < tlen && S[p] == T[j]) p++, j++;
            extend[i] = j;
            a = i;
        } else extend[i] = Next[i-a];
    }
}

int main()
{
    cin>>S;
    int len = strlen(S);
    GetNext(S, Next);
    long long ans = ;
    for(int i = ; i < len; i++)  ans += Next[i];
    cout<<ans<<endl;
    return ;
}