LEET-T0060: Permutation Sequence

#include <bits/stdc++.h>
using namespace std;

const int N = 9 + 5;

string str;
int cnt;
bool visited[N];

bool recur(int n, int k, int i){
    if(i == 0){
        ++cnt;
        if(cnt == k){
            return true;
        }
        return false;
    }
    for(int j = 0; j < n; ++j){
        if(!visited[j]){
            str += (char)j + 1 + '0';
            visited[j] = true;
            if(recur(n, k, i - 1)){
                return true;
            }
            str.pop_back();
            visited[j] = false;
        }
    }
    return false;
}

string getPermutation(int n, int k){
    if(recur(n, k, n)){
        return str;
    }
    return "";
}

int main(){

    int n, k;
    scanf("%d%d", &n, &k);
    cout << getPermutation(n, k);

    return 0;
}