Blue Jeans POJ 3080 寻找多个串的最长相同子串

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<vector>
#include<string>
using namespace std;
typedef long long LL;
#define MAXN 63
/*
枚举所有子串，用KMP算法检查是否出现过，选择其中的最优解
*/
char s[MAXN][MAXN];
int next[MAXN];
void kmp_pre(char x[])
{
    int i,j,m=strlen(x);
    j = next[0] = -1;
    i = 0;
    while(i<m)
    {
        if(j!=-1&&x[i]!=x[j])
            j = next[j];
        next[++i] = ++j;
    }
}
bool kmp(char x[],char y[])
{
    int i,j,ans = 0,m=strlen(x),n=strlen(y);
    kmp_pre(x);
    i=j=0;
    while(i<n)
    {
        while(j!=-1&&y[i]!=x[j])
            j = next[j];
        i++;
        j++;
        if(j>=m)
            return true;
    }
    return false;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        int m;
        char ans[MAXN] = "Z";
        scanf("%d",&m);
        for(int i=0;i<m;i++)
            scanf("%s",s[i]);
        for(int len=60;len>=3;len--)
            for(int i=0;i<=60-len;i++)
            {
                char b[MAXN] = {0};
                strncpy(b,s[0]+i,len);
                //cout<<len<<":"<<b<<endl;
                int j;
                for(j=1;j<m;j++)
                {
                    if(!kmp(b,s[j]))
                        break;
                }
                if(j==m&&strcmp(ans,b)>0)
                {
                    strcpy(ans,b);
                }
                if(ans[0]!=‘Z‘&&i==60-len)
                {
                    i = 999;
                    len = 0;
                }
            }
            if(ans[0]==‘Z‘)
                printf("no significant commonalities\n");
            else 
                printf("%s\n",ans);
    }
    return 0;
}