백준 사다리 조작 C++

#include <iostream>
#include <cstring>

using namespace std;
int map[31][11];
int n, m, h;
int linenum;
bool flag;

void dfs(int j, int count) {
	if (flag == true)
		return;

	if (count == linenum) {
		flag = true;

		for (int i = 1; i <= n; i++) {
			int index = i;
			for (int j = 0; j < h; j++) {
				if ( map[j][index] == 1) 
					index++;
				else if (index>1 && map[j][index - 1] == 1) 
					index--;
			}
			if (index != i) {
				flag = false;
				break;
			}
		}
		return;
	}

	for (int x = j; x < h; x++) {
		for (int y = 1; y < n; y++) {
			if (map[x][y - 1]!= 1 && map[x][y]!=1 && map[x][y + 1]!=1) {
				map[x][y] = 1;
				dfs(x, count + 1);
				map[x][y] = -1;
			}
		}
	}
	return;
}

int main(void) {
	cin >> n >> m >> h;

	memset(map, -1, sizeof(map));
	for (int i = 0; i < m; i++) {
		int x, y;
		cin >> x >> y;
		map[x-1][y] = 1;
	}
	
	for (int i = 0; i <= 3; i++) {
		linenum = i;
		dfs(0, 0);
		if (flag == true) {
			cout << i << endl;
			return 0;
		}
	}
	cout << -1 << endl;
	return 0;
}