[C++] 15654 - N과 M (5)

문제 링크 : https://www.acmicpc.net/problem/15654

15654번: N과 M (5)

 

 

 

 

#include<iostream>
#include<algorithm>
#define endl '\n'
 
int isuse[10];    // used or not used
int arr[10];    // backtracking array
int N, M;
int store[10];    // save number
 
using namespace std;
 
void NM(int k){
 
    if(k == M)    // if k == M, arr is fulled.
    {
        for(int i = 0; i < k; ++i)    // print arr
            cout << arr[i] << ' ';
        cout << endl;
        return;                        // return
    }
 
    for(int i = 0; i < N; ++i)
    {
        if(!isuse[i])                // if not used
        {
            isuse[i] = 1;            // used BIT on
            arr[k] = store[i];        // arr[k] = store[i].
            /*
            store[i] == 0 means store[i] is not used.
            so if will use value of store[i], turn store[i] BIT on.
            */
            NM(k+1);
            isuse[i] = 0;            // if end of backtracking, turn used BIT off.
        }
    }
 
}
 
int main(void)
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
 
    cin >> N >> M;
 
    for(int i = 0; i < N; ++i)
        cin >> store[i];
    
    sort(store, store+N);
 
    NM(0);
 
    return 0;
}