学步园

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2594

题目大意：给定两个字符串s1,s2,求最长的s1前缀ss使得ss为s2的后缀，比如s1 = "youloveme",s2 = "fuckyou"，所求ss即为“you"

题目思路：将s1和s2拼为s3，在s3中求next数组，最终判断最后一个字母的next值，我的代码中next+1才代表自身匹配数

测试数据:：

abc abcd
hellolleh hello
hello ello
ello hello
hellolleh olleh
clinton homer
aaaaa aaaaaa
clinton homer
riemann marjorie
abcba bcba

代码：

#include <stdio.h>
#include <string.h>
#define MAX 50010


int next[MAX*2],maxx,l1,l2;
char s1[MAX],s2[MAX],s3[MAX*2],ans[MAX];


void getnext(char *s) {

	int i,j,k;
	i = 0,j = -1;
	next[0] = -1;
	while (s[i]) {

		if (j == -1 || s[i] == s[j])
			i++,j++,next[i] = j;
		else j = next[j];
	}


	if (next[i] > -1) {

		maxx = next[i];
		for (j = 0; j < maxx; ++j)
			ans[j] = s[j];
		ans[j] = '\0';
	}
}
void Solve() {

	strcpy(s3,s1);
	strcat(s3,"*");
	strcat(s3,s2);
	getnext(s3);
}


int main()
{
	int i,j,k;


	while (scanf("%s%s",s1,s2) != EOF) {

		memset(next,-1,sizeof(next));
		maxx = -2;
		l1 = strlen(s1);
		l2 = strlen(s2);
		Solve();


		if (maxx <= 0) printf("0\n");
		else printf("%s %d\n",ans,maxx);
	}
}