Cyclic Nacklace

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 7375 Accepted Submission(s): 3210

Problem Description

CC always becomes very depressed at the end of this month, he has checked his credit card yesterday, without any surprise, there are only 99.9 yuan left. he is too distressed and thinking about how to tide over the last days. Being inspired by the entrepreneurial spirit of "HDU CakeMan", he wants to sell some little things to make money. Of course, this is not an easy task.

As Christmas is around the corner, Boys are busy in choosing christmas presents to send to their girlfriends. It is believed that chain bracelet is a good choice. However, Things are not always so simple, as is known to everyone, girl's fond of the colorful decoration to make bracelet appears vivid and lively, meanwhile they want to display their mature side as college students. after CC understands the girls demands, he intends to sell the chain bracelet called CharmBracelet. The CharmBracelet is made up with colorful pearls to show girls' lively, and the most important thing is that it must be connected by a cyclic chain which means the color of pearls are cyclic connected from the left to right. And the cyclic count must be more than one. If you connect the leftmost pearl and the rightmost pearl of such chain, you can make a CharmBracelet. Just like the pictrue below, this CharmBracelet's cycle is 9 and its cyclic count is 2:

Now CC has brought in some ordinary bracelet chains, he wants to buy minimum number of pearls to make CharmBracelets so that he can save more money. but when remaking the bracelet, he can only add color pearls to the left end and right end of the chain, that is to say, adding to the middle is forbidden.
CC is satisfied with his ideas and ask you for help.

Input

The first line of the input is a single integer T ( 0 < T <= 100 ) which means the number of test cases.
Each test case contains only one line describe the original ordinary chain to be remade. Each character in the string stands for one pearl and there are 26 kinds of pearls being described by 'a' ~'z' characters. The length of the string Len: ( 3 <= Len <= 100000 ).

Output

For each case, you are required to output the minimum count of pearls added to make a CharmBracelet.

Sample Input

3 aaa abca abcde

Sample Output

0 2 5

Author

possessor WC

Source

HDU 3rd “Vegetable-Birds Cup” Programming Open Contest

题意：补最少的字符，让字符串为一个循环的字符串

思路：求出字符串循环节的长度，我是没想出来怎么求，是网上看到有人说为 len - Next[ len ]，自己纸上模拟了了一下才觉得好像是这么回事，的确想不出；这里的Next数组是 kmp算法里面 getnext函数里面求的一个数组，kmp我就不讲了，这里有一个结论就是循环字节的长度 = 字符总长度 - Next 【字符总长度】；知道字符循环字节的长度，对总长取余就行了；

#include<cstdio>
#include<cstring>
#include<iostream>
#include<queue>
#include<cmath>
#include<algorithm>
#include<string>

using namespace std;

#define Maxn 100010
#define INF 0x3f3f3f3f

int Next[Maxn];
char a[Maxn];

void getNext (char ptr[]) {
    memset(Next,0,sizeof(Next));
    Next[0] = -1;
    int k = -1, j = 0, len = strlen(ptr);
    while (j < len) {
        if(k == -1 || ptr[k] == ptr[j] ) {
                ++j; ++k;
                Next[j] = k;
            } else k = Next[k];
    }
    int tmp = len - Next[len];
    if(len%tmp == 0 && tmp != len) printf("0\n");
    else printf("%d\n",tmp - len%tmp);
}

int main (void)
{
    int N;
   scanf("%d",&N);
        for (int i = 0; i < N; ++i) {
            scanf(" %s",a);
            getNext(a);
        }
    return 0;
}

HDU 3746 Cyclic Nacklace 【字符串循环节长度】

Cyclic Nacklace

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