HUST-1010: The Minimum Length

KMP

题目描述

There is a string A. The length of A is less than 1,000,000. I rewrite it again and again. Then I got a new string: AAAAAA...... Now I cut it from two different position and get a new string B. Then, give you the string B, can you tell me the length of the shortest possible string A. For example, A="abcdefg". I got abcdefgabcdefgabcdefgabcdefg.... Then I cut the red part: efgabcdefgabcde as string B. From B, you should find out the shortest A.

输入

Multiply Test Cases. For each line there is a string B which contains only lowercase and uppercase charactors. The length of B is no more than 1,000,000.

输出

For each line, output an integer, as described above.

样例输入

bcabcab
efgabcdefgabcde

样例输出

3
7

题意：求一个串的最小循环节。

• 代码：

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e6 + 5;
char s[maxn];
int Next[maxn];
void getNext(char s[])
{
    int len = strlen(s);
    Next[0] = -1;
    int j = 0, k = -1;
    while(j < len)
    {
        if(k == -1 || s[j] == s[k])
            Next[++j] = ++k;
        else
            k = Next[k];
    }
}
int main()
{
    while(scanf("%s", s) != EOF)
    {
        int l = strlen(s);
        getNext(s);
        printf("%d\n", l - Next[l]);
    }
    return 0;
}