HDU 3746 Cyclic Nacklace KMP

题目地址：http://acm.hdu.edu.cn/showproblem.php?pid=3746

KMP算法——

AC代码：

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <list>
#include <deque>
#include <queue>
#include <iterator>
#include <stack>
#include <map>
#include <set>
#include <algorithm>
#include <cctype>
using namespace std;

typedef long long LL;
const int N=200005;
const LL II=100000000;
const int INF=0x3f3f3f3f;
const double PI=acos(-1.0);

int next[N],len,nextval[N];
char str[N];

void getnext(char *p)
{
    int j=0,k=-1;
    next[0]=-1;
    while(j<len)//len是p的长度
    {
        if(k==-1||p[j]==p[k])
        {
            j++;    k++;
            next[j]=k;
        }
        else
            k=next[k];
    }
}

void getnextval(const char *p)
{
    int i = 0,j =-1;
    nextval[0]=-1;
    while(i!=len)
    {
        if(j==-1||p[i]==p[j])
        {
            ++i;++j;
            if(p[i]!=p[j])
                nextval[i]=j;
            else
                nextval[i]=nextval[j];
        }
        else
            j=nextval[j];
    }
}

int main()
{
    int i,j,T;
    cin>>T;
    while(T--)
    {
        scanf("%s",str);
        len=strlen(str);
        getnext(str);
        int min_repeat=len-next[len];
        if(min_repeat==len)
            printf("%d\n",len);
        else if(len%min_repeat==0)
            printf("0\n");
        else
            printf("%d\n",min_repeat-len%min_repeat);
    }
    return 0;
}