UVA 10252

Problem G

Common Permutation

Input: standard input

Output: standard output

Time Limit: 4 seconds

Memory Limit: 32 MB

 

Given two strings of lowercase letters, a and b, print the longest string x of lowercase letters such that there is a permutation of x that is a subsequence of a and there is a permutation of x that is a subsequence of b.

 

Input

Input file contains several lines of input. Consecutive two lines make a set of input. That means in the input file line 1 and 2 is a set of input, line 3and 4 is a set of input and so on. The first line of a pair contains a and the second contains b. Each string is on a separate line and consists of at most 1000 lowercase letters.

 

Output

For each set of input, output a line containing x. If several x satisfy the criteria above, choose the first one in alphabetical order.

 

Sample Input:

pretty

women

walking

down

the

street

Sample Output:

e

nw

et

虽然这道题比较水 ， 但是其中有些小技巧还是值得学习的 ， 比如如何确定输入结束 ， gets（a） == NULL

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

using namespace std;
char a[1005];
char b[1005];
int x[26];
int y[26];
int main()
{
    //freopen("in.txt" , "r" , stdin);
    while(1)
    {
        memset(x ,0 , sizeof(x));
        memset(y , 0 , sizeof(y));
        if(gets(a) == NULL)
        {
            break;
        }
        gets(b);
        int num = 0;
        for(int i = 0 ; i < strlen(a) ; i++)
        {
            x[a[i] - 'a']++;
        }
        for(int i = 0 ; i < strlen(b) ; i++)
        {
            y[b[i] - 'a']++;
        }
        for(int i = 0 ; i < 26 ; i++)
        {
            if(x[i]&&y[i])
            {
                for(int j = 0 ; j < min(x[i] , y[i]) ; j++)
                {
                    printf("%c" , i + 'a');
                }
            }
        }
        cout << endl;
    }
    return 0;
}
/*

*/