P1162 填涂颜色

#include <iostream>
#include <stdio.h>
#include <algorithm>
#include <queue>
using namespace std;
int m[100][100];
int dir[][2] = { {1,0},{0,1},{-1,0},{0,-1} };
int n;
struct node {
	int x, y;
	node(int a, int b) {
		x = a;
		y = b;
	}
};
bool check(int a, int b) {
	if (a > n || a < 0 || b > n || b < 0)
		return false;
	return true;
}
void bfs() {
	queue<node> q;
	for (int i = 0; i < n; i++) {
		if (m[i][0] == 0)
			q.push(node(i, 0));
		if (m[0][i] == 0)
			q.push(node(0, i));
		if (m[i][n-1] == 0)
			q.push(node(i, n-1));
		if (m[n-1][i] == 0)
			q.push(node(n-1, i));
	}
	while (!q.empty()) {
		node t = q.front();
		q.pop();
		m[t.x][t.y] = 2;
		for (int i = 0; i < 4; i++) {
			int xx = t.x + dir[i][0];
			int yy = t.y + dir[i][1];
			if(m[xx][yy] == 0 && check(xx, yy))
				q.push(node(xx, yy));
		}
	}
}
int main(){

	scanf("%d", &n);
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			scanf("%d", &m[i][j]);
		}
	}
	bfs();
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			if (m[i][j] == 2)
				cout << 0 << " ";
			else if (m[i][j] == 0)
				cout << 2 << " ";
			else
				cout << 1 << " ";
		}
		cout << endl;
	}

	return 0;
}