[hdu][2203][亲和串]

题目：http://acm.hdu.edu.cn/showproblem.php?pid=2203

给定两个字符串s1和s2,如果能通过s1循环移位，使s2包含在s1中，那么我们就说s2 是s1的亲和串。

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

const int MAXV = 200000+10;

void kmp(char in[], int len, int path[])
{
    int i, j = -1; path[0] = -1;
    for (i = 1; i < len; i++)
    {
        while (j >= 0 && in[j+1] != in[i]) j = path[j];
        if (in[j+1] == in[i]) j++;
        path[i] = j;
    }
}

char s1[MAXV], s2[MAXV];
int p[MAXV];

int main()
{
    int l1, l2, ok;
    while (scanf("%s%s", s1, s2) != EOF)
    {
        l1 = strlen(s1); l2 = strlen(s2);
        ok = 0;
        if (l1 < l2)
        {
            printf("no\n");
            continue;
        }
        kmp(s2, l2, p);
        int i, j=-1;
        for (i = l1; i < l1+l2; i++) s1[i] = s1[i-l1];
        s1[i] = '\0';
        for (i = 0; i < l1+l2 && !ok; i++)
        {
            while (j > -1 && s1[i] != s2[j+1]) j = p[j];
            if (s2[j+1] == s1[i]) j++;
            if (j == l2-1)
            {
                printf("yes\n");
                ok = 1;
            }
        }
        if (!ok) printf("no\n");
    }
    return 0;
}