【Kmp】Blue Jeans POJ

Link：http://poj.org/problem?id=3080

//#include <bits/stdc++.h>#include <cstdio>#include <cstring>#include <algorithm>#include <iostream>using namespace std;typedef long long LL;/*题意：找出n个串中最长的公共串，并且要求字典序最大题解：枚举第一字符串的子串*/const int N = 66;int nex[N];void getnext(string s){    memset(nex,0,sizeof(nex));    int len = s.length();    nex[0] = -1;    int k = -1;    for(int i = 1; i < len; i++){        while(k!=-1 && s[k+1]!=s[i])            k = nex[k];        if(s[k+1]==s[i])            k++;        nex[i] = k;    }}bool Kmp(string s,string p){    int len = s.length();    int lenp = p.length();    int k = -1;    for(int i = 0; i < len; i++){        while(k!=-1 && p[k+1]!=s[i])            k = nex[k];        if(p[k+1]==s[i])            k++;        if(k == lenp-1)            return true;    }    return false;}struct asd{    string s;}ans[N],now[N*N],aa[N];bool cmp(asd a, asd b){    if(a.s.length() != b.s.length())        return a.s.length() > b.s.length();    return a.s < b.s;}int init(){    int len = aa[0].s.length();    int k = 0;    for(int leg = 3; leg <= len; leg++){        for(int i = 0; i+leg <= len; i++)            now[k++].s = aa[0].s.substr(i,leg);    }    return k;}int main(){    int T;    scanf("%d",&T);    while(T--){        int n;        cin >> n;        for(int i = 0; i < n; i++)            cin >> aa[i].s;        int k = init();        sort(now,now+k,cmp);        int f = 0;        for(int i = 0; i < k; i++)        {            //cout <<now[i].s << endl;            getnext(now[i].s);            int flag = 0;            for(int j = 1; j < n; j++){                if(!Kmp(aa[j].s,now[i].s))                    flag = 1;            }            if(!flag)            {                f = 1;                cout << now[i].s << endl;                break;            }        }        if(!f)  cout << "no significant commonalities" << endl;    }    return 0;}