UVa 10252 - Common Permutation Solution

#include<iostream>
#include<list>
#include<string>
#include<cstring>
#include<sstream>
#include<cctype>
#include<string.h>
#include<algorithm>
#include<cmath>
#include<stack>
#include<fstream>
#include<cstdlib>
#include<vector>
#include<map>
#include<set>
#include<utility>
#include<iomanip>
#include<queue>

using namespace std;

#define INF (1<<29)
#define SET(a) memset(a,-1,sizeof(a))
#define ALL(a) a.begin(),a.end()
#define CLR(a) memset(a,0,sizeof(a))
#define FILL(a,v) memset(a,v,sizeof(a))
#define PB push_back
#define FOR(i,n) for(int i = 0;i<n;i++)
#define PI acos(-1.0)
#define EPS 1e-9
#define MP(a,b) make_pair(a,b)
#define min3(a,b,c) min(a,min(b,c))
#define max3(a,b,c) max(a,max(b,c))
#define READ(f) freopen(f, "r", stdin)
#define WRITE(f) freopen(f, "w", stdout)
#define LL long long
#define MX 100000
#define MOD 1000000007


main()
{
    char s1[1010],s2[1010];
    map<char, int>freq;
    while(gets(s1))
    {
        gets(s2);
        int l1=strlen(s1);
        sort(s1,s1+l1);
        int l2=strlen(s2);
        sort(s2,s2+l2);

        freq.clear();

        for(int i=0;i<l1;i++)
            freq[s1[i]]++;
        for(int i=0;i<l2;i++)
            if(freq[s2[i]])
            {
                cout<<s2[i];
                freq[s2[i]]--;
            }
        cout<<endl;
    }
}