ABC345 D問題（Tiling）を解く

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

int tile[10][10];
int n;
int h, w;
vector<int> a;
vector<int> b;
vector<bool> used;

void copy_tile(int dst[10][10], int src[10][10])
{
	for (int i = 0; i < 10; ++i) {
		for (int j = 0; j < 10; ++j) {
			dst[i][j] = src[i][j];
 		}
	}
}

bool rec(int now[10][10])
{
	int t[10][10];
	copy_tile(t, now);

	int s_h = -1;
	int s_w = -1;
	for (int i = 0; i < h; ++i) {
		for (int j = 0; j < w; ++j) {
			if ((t[i][j] == 0)&&(s_h == -1)) {
				s_h = i;
				s_w = j;
			}
 		}
	}
	if (s_h == -1) {
		return true;
	}

	for (int i = 1; i <= n; ++i) {
		if (!used[i]) {
			bool is_ok = true;
			if ((s_h + a[i] - 1 < h)&&(s_w + b[i] - 1 < w)) {
				for (int ih = 0; ih < a[i]; ++ih) {
					for (int iw = 0; iw < b[i]; ++iw) {
						if (t[s_h + ih][s_w + iw] != 0) {
							is_ok = false;
						} else {
							t[s_h + ih][s_w + iw] = i;
						}
					}
				}
				if (is_ok) {
					used[i] = true;
					if (rec(t)) {
						return true;
					}
					used[i] = false;
					copy_tile(t, now);
				}
			}
			if (a[i] == b[i]) {
				continue;
			}

			is_ok = true;
			if ((s_h + b[i] - 1 < h)&&(s_w + a[i] - 1 < w)) {
				for (int ih = 0; ih < b[i]; ++ih) {
					for (int iw = 0; iw < a[i]; ++iw) {
						if (t[s_h + ih][s_w + iw] != 0) {
							is_ok = false;
						} else {
							t[s_h + ih][s_w + iw] = i;
						}
					}
				}
				if (is_ok) {
					used[i] = true;
					if (rec(t)) {
						return true;
					}
					used[i] = false;
					copy_tile(t, now);
				}
			}
		}
	}

	return false;
}

int main()
{
	cin >> n >> h >> w;
	a.resize(n + 1);
	b.resize(n + 1);
	used.assign(n + 1, false);
	for (int i = 1; i <= n; ++i) {
		cin >> a[i] >> b[i];
	}

	if (rec(tile)) {
		cout << "Yes" << endl;
	} else {
		cout << "No" << endl;
	}

	return 0;
}