Period (KMP算法 最小循环节 最大重复次数)

Period (KMP算法 最小循环节 最大重复次数)

题目

给出一个字符串s,问在[0, i]区间是否有完整的循环节,若有,输出i并输出循环次数
Input
The input file consists of several test cases. Each test case consists of two lines. The first one contains N (2 <= N <= 1 000 000) – the size of the string S. The second line contains the string S. The input file ends with a line, having the number zero on it.
Output
For each test case, output “Test case #” and the consecutive test case number on a single line; then, for each prefix with length i that has a period K > 1, output the prefix size i and the period K separated by a single space; the prefix sizes must be in increasing order. Print a blank line after each test case.
ample Input
3
aaa
12
aabaabaabaab
0
Sample Output
Test case #1
2 2
3 3

Test case #2
2 2
6 2
9 3
12 4

思路

见 这篇博客
然后枚举就好

题解

#include 
#include 
#define N 1000020
using namespace std;

char str[N];
int nex[N];
int len;
void getNext()
{
    int i = -1, j = 0;
    nex[0] = -1;
    while (j < len)
    {
        if (i == -1 || str[i] == str[j])
            nex[++j] = ++i;
        else
            i = nex[i];
    }
}

int main()
{
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    int k, kase = 1;
    while (cin >> k)
    {
        if(k==0) break;
        cout << "Test case #" << (kase++) << endl;
        cin >> str;
        len = strlen(str);
        getNext();
        for (int i = 2; i <= k; i++)
        {
            int son = i - nex[i];
            if (i % son == 0 && nex[i] != 0)
            {
                cout<