i tried 6_dnmc

#include <iostream>
#include <stdio.h>
#include <vector>

using namespace std;

struct stack{
    int inf;
    stack* next;
};

stack *init(){
    return NULL;
}

void push(stack *&h, int x){
    stack *top = new stack();
    top->inf = x;
    top->next = h;
    h = top;
}

int top(stack *&h){
    return h->inf;
}

int pop(stack *&h){
    int i = h->inf;
    stack *cur = h;
    h=h->next;
    delete cur;
    return i;
}

int main(){
#ifdef _DEBUG
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
	int n;
	cin >> n;
	vector<vector<int>> v(n, vector<int> (n));
	vector<bool> used(n, false);
	cout << "Fill in the matrix of adjacency: press 1 for yes, 0 for no\n";
	for(int i = 0; i < n; i++){
		for(int j = 0; j < n; j++){
			cin >> v[i][j];
		}
	}
	stack *h = init();
	stack *res = init();
	for(int i = 0; i < n; i++){
		push(h, i);
		while(h){
			int cur = top(h);
			//if(used[cur]){
			//	pop(h);
			//	break;
			//}
			bool flag = false;//shows true if there are no unused tops left
			int j = 0;
			while(j < n){
				if(v[cur][j] && !used[j]){
					push(h, cur);
					break;
				}
				else j++;
			}
			if(flag){
				used[cur] = true;
				pop(h);
				push(res, pop(h));
			}
		}
	}
	while(res){
		cout << pop(res) << " ";
	}


	return 0;
}