Cyclic Nacklace（HDU 3746）

[kuangbin带你飞]专题十六 KMP & 扩展KMP & Manacher

D - Cyclic Nacklace

Time Limit:1000MS
Memory Limit:32768KB

Description

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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.

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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 ).

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

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Sample Input

3aaaabcaabcde 

Sample Output

025 

题目大意：

abcabca就是差了个bc
aaaaaaa就是没差
abcabcd就是差了abcabcd才串成珠子
就是这个意思

分析:

就是求循环节之后做结果处理

//这个就是结果处理int round =l-n[l-1];int l = p.length();int showr(int r,int l){    return l%r ? r - l%r : r == l ? l : 0;}

前天学回kmp之后今天才懂得怎么用next数组求循环节

AC代码：

#include<iostream>#include<algorithm>#include<vector>#include<string.h>#include<string>using namespace std;const int maxn = 100001;int n[maxn];string p;void getnext(int l){    n[0]=0;    for (int i = 1, j = 0; i < l; i++)    {        while (j&&p[i] != p[j])            j = n[j-1];        if (p[i] == p[j])j++;        n[i] = j;    }}int showr(int r,int l){    return l%r ? r - l%r : r == l ? l : 0;}int main(){    int cas;    cin >> cas;    while (cas--)    {        memset(n, 0, sizeof(n));        cin >> p;        int l = p.length();        getnext(l);        int round =l-n[l-1];        cout << showr(round,l) << endl;    }}

最小循环节看的ppt