HDU 2594 Simpsons’ Hidden Talents

Simpsons’ Hidden Talents

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 5061    Accepted Submission(s): 1845

Problem Description

Homer: Marge, I just figured out a way to discover some of the talents we weren’t aware we had.
Marge: Yeah, what is it?
Homer: Take me for example. I want to find out if I have a talent in politics, OK?
Marge: OK.
Homer: So I take some politician’s name, say Clinton, and try to find the length of the longest prefix
in Clinton’s name that is a suffix in my name. That’s how close I am to being a politician like Clinton
Marge: Why on earth choose the longest prefix that is a suffix???
Homer: Well, our talents are deeply hidden within ourselves, Marge.
Marge: So how close are you?
Homer: 0!
Marge: I’m not surprised.
Homer: But you know, you must have some real math talent hidden deep in you.
Marge: How come?
Homer: Riemann and Marjorie gives 3!!!
Marge: Who the heck is Riemann?
Homer: Never mind.
Write a program that, when given strings s1 and s2, finds the longest prefix of s1 that is a suffix of s2.

 

Input

Input consists of two lines. The first line contains s1 and the second line contains s2. You may assume all letters are in lowercase.

 

Output

Output consists of a single line that contains the longest string that is a prefix of s1 and a suffix of s2, followed by the length of that prefix. If the longest such string is the empty string, then the output should be 0.
The lengths of s1 and s2 will be at most 50000.

 

Sample Input

clinton homer riemann marjorie

 

Sample Output

0 rie 3

 
題意是求最長主串的前綴與模式串後綴匹配。
這種，只要連接後，便可利用KMP的功能，來實現找到其前綴後綴的最大匹配。
注意中間需要一個不會出現的字符進行隔開，以防出現自我匹配的情況。

代碼如下；

/*************************************************************************
	> File Name: Simpsons_Hidden_Talents.cpp
	> Author: Zhanghaoran
	> Mail: [email protected]
	> Created Time: Wed 02 Dec 2015 05:14:12 PM CST
 ************************************************************************/

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <cstdlib>

using namespace std;

void preKMP(char x[], int m, int kmpnext[]){
    int i, j;
    i = 0;
    j = kmpnext[0] = -1;
    while(i < m){
        while(j != -1 && x[i] != x[j])
            j = kmpnext[j];
        if(x[++ i] == x[++ j])
            kmpnext[i] = kmpnext[j];
        else 
            kmpnext[i] = j;
    }
}

int nexti[100010];

int main(void){
    char str1[100010];
    char str2[50010];
    while(~(scanf("%s%s", str1, str2))){
        int temp1 = strlen(str1);
        str1[temp1] = '&';
        str1[temp1 + 1] = '\0';
        strcat(str1, str2);
        int temp = strlen(str1);
        preKMP(str1, temp, nexti);
        if(nexti[temp]){
            for(int i  = 0; i < nexti[temp]; i ++){
                printf("%c", str1[i]);
            }
            cout << " ";
            cout << nexti[temp] << endl;
        }
        else
            cout << nexti[temp] << endl;
    }
}