Power Strings

最新推荐文章于 2023-06-30 19:30:28 发布

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最新推荐文章于 2023-06-30 19:30:28 发布

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本文链接：https://blog.youkuaiyun.com/weixin_43841060/article/details/85081607

本文探讨了KMP算法中next数组的应用，通过分析字符串的循环节来判断其是否为某个基本字符串的幂次重复。文章提供了一个C++实现的例子，用于找出输入字符串的最大循环节长度。

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p.s. KMP.next数组循环节应用

Power Strings

Time Limit: 1000 ms Memory Limit: 65536 KiB

Problem Description

Given two strings a and b we define a*b to be their concatenation. For example, if a = "abc" and b = "def" then a*b = "abcdef". If we think of concatenation as multiplication, exponentiation by a non-negative integer is defined in the normal way: a^0 = "" (the empty string) and a^(n+1) = a*(a^n).

Input

Each test case is a line of input representing s, a string of printable characters. The length of s will be at least 1 and will not exceed 1 million characters. A line containing a period follows the last test case.

Output

For each s you should print the largest n such that s = a^n for some string a.

Sample Input

abcd
aaaa
ababab
.

Sample Output

1
4
3

题目链接：

http://acm.sdut.edu.cn/onlinejudge2/index.php/Home/Contest/contestproblem/cid/2710/pid/2475

#include <bits/stdc++.h>

using namespace std;

int nextnum[1000010];
char s[1000010];

void get_next(char s[]){
    int i=0,j=-1,len=strlen(s);
    nextnum[0]=-1;
    while(i<len)
    {
        if(j==-1||s[i]==s[j])
        {
            i++;
            j++;
            nextnum[i]=j;
        }
        else
        j=nextnum[j];
    }
}

int main()
{
    while(cin >> s&&s[0]!='.')
    {
        int len=strlen(s);
        get_next(s);
        if(len%(len-nextnum[len])==0)
        cout << len/(len-nextnum[len]) << endl;
        else
        cout << 1 << endl;
    }
    return 0;
}