POJ 1961 Period (KMP)

利用next数组求解

#include <cstdio>
#include <cstring>
using namespace std;
const int maxn = 1000000 + 10;
char str[maxn];
int next[maxn];
int len;
int cas;
int n;
 
void getNext()
{
    int i = 0, j = -1;
    next[0] = -1;
    while (i != len){
        if (j == -1 || str[i] == str[j]){
            next[++i] = ++j;
        }
        else
            j = next[j];
    }
}
 
int main()
{
    cas = 0;
    while (scanf("%d", &len), len){
        scanf("%s", str);
        printf("Test case #%d\n", ++cas);
        getNext();
        for (int i = 2; i <= len; i++){
            if (i % (i - next[i]) == 0 && i / (i - next[i]) != 1){
                printf("%d %d\n", i, i / (i - next[i]));
            }
        }
        printf("\n");
    }
    return 0;
}