KMP

代码

int fail[maxn];
void get_fail(int arry[], int l){

    fail[0] = fail[1] = 0;
    for(int i = 2, j = 0; i <= l; ++i){
        while(j > 0 && arry[i] != arry[j+1]) j = fail[j];
        if(arry[i] == arry[j+1]) ++j;
        fail[i] = j;
    }
}

int kmp(int arry[], int p, int mode[], int q){

    get_fail(mode,  q);
    for(int i = 1, j = 0; i <= p; ++i){
        while(j > 0 && arry[i] != mode[j+1]) j = fail[j];
        if(arry[i] == mode[j+1]) ++j;
        if(j == q) return i - q + 1;
    }

    return 0;
}