16943번 숫자 재배치

https://www.acmicpc.net/problem/16943

기본적인 백트래킹 문제이다.

#include <iostream>
#include <queue>
#include <stack>
#include <cstdio>
#include <vector>
#include <cstring>
#include <string>
#include <math.h>
#include <algorithm>
#include <map>
#include <set>
#include <sstream>
#include <tuple>
 
#pragma warning(disable:4996)  
#pragma comment(linker, "/STACK:336777216")
 
using namespace std;
 
string A, B;
 
vector<char> v;
 
int MAX = -1, b = 0;
 
bool use[12] = { false, };
 
void simulation(string s)
{
    if (s.length() == A.length())
    {
        if (s.at(0) == '0') return;
 
        int a = atoi(s.c_str());
 
        if (a <= b) MAX = max(MAX, a);
 
        return;
    }
 
    for (int i = 0; i < v.size(); i++)
        if (!use[i])
        {
            s += v.at(i);
            use[i] = true;
            
            simulation(s);
 
            s = s.substr(0, s.length() - 1);
            use[i] = false;
        }
}
 
int main(void)
{
    MAX = -1;
 
    cin >> A >> B;
 
    for (int i = 0; i < A.length(); i++) v.push_back(A.at(i));
    
    b = atoi(B.c_str());
 
    simulation("");
 
    printf("%d\n", MAX);
 
    return 0;
}