HDU 1358 Period（KMP+最小循环节）题解

思路：

这里只要注意一点，就是失配值和前后缀匹配值的区别，不懂的可以看看这里，这题因为对子串也要判定，所以用前后缀匹配值，其他的按照最小循环节做

代码：

#include<iostream>
#include<algorithm>
const int N = 1000000+5;
const int INF = 0x3f3f3f3f;
using namespace std;
int fail[N];
char p[N];
void getFail(){
     fail[0] = -1;
     int j = 0,k = -1;
     int len = strlen(p);
     while(j <= len){
        if(k == -1 || p[j] == p[k]){
            fail[++j] = ++k;
        }
        else{
            k = fail[k];
        }
     }
}
/*int KMP(){
    int num = 0;
    getFail();
    int i = 0,j = 0;
    int lent = strlen(t),lenp = strlen(p);
    while(i < lent){
        if(j == -1 || t[i] == p[j]){
            i++;
            j++;
            if(j == lenp) num++;
        }
        else{
            j = fail[j];
        }
    }
    return num;
}*/
int main(){
    int n,Case = 1;
    while(scanf("%d",&n) && n){
        scanf("%s",p);
        printf("Test case #%d\n",Case++);
        getFail();
        int num = 0;
        for(int i = 2;i <= n;i++){
            if(fail[i] == -1) continue;
            int c = i - fail[i];
            if(i == c) continue;
            else if(i % c == 0) printf("%d %d\n",i,i / c);
        }
        printf("\n");
    }
    return 0;
}