백준 1113번 수영장 만들기 C++

출처 : https://www.acmicpc.net/problem/1113

 

bfs를 돌면서 물을 채울 수 있다면 일단 job 큐에 넣어두고 마지막까지 탐색을 마쳤을 때 물이 새는 곳이 없다면

그때 job큐를 돌면서 물을 채워주는 방식으로 문제를 해결하였다.

 

#include <iostream>
#include <string>
#include <vector>
#include <math.h>
#include <algorithm>
#include <utility>
#include <stack>
#include <queue>
#include <math.h>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <iomanip>

using namespace std;
using ll = long long;

int n, m;

int dRow[4] = { -1,0,1,0 };
int dCol[4] = { 0,1,0,-1 };

vector<vector<int>> board(50, vector<int>(50));
vector<vector<bool>> found(50, vector<bool>(50, false));

void RefreshFound() {
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			found[i][j] = false;
		}
	}
}

int bfs(int row, int col) {
	RefreshFound();
	found[row][col] = true;
	queue<pair<int, int>> q;
	queue<pair<int, int>> job;
	q.push({ row,col });
	bool isPossible = true;
	int minWall = 10;
	int maxHeight = 0;
	int ret = 0;
	while (!q.empty()) {
		auto curr = q.front();
		q.pop();
		maxHeight = max(maxHeight, board[curr.first][curr.second]);
		job.push({ curr.first,curr.second });
		for (int i = 0; i < 4; i++) {
			int nextRow = curr.first + dRow[i];
			int nextCol = curr.second + dCol[i];
			if (nextRow < 0 || nextRow >= n || nextCol < 0 || nextCol >= m) {
				isPossible = false;
				break;
			}
			if (found[nextRow][nextCol]) continue;
			if (board[nextRow][nextCol] > maxHeight) {
				minWall = min(minWall, board[nextRow][nextCol]);
				continue;
			}
			found[nextRow][nextCol] = true;
			q.push({ nextRow,nextCol });
		}
	}
	if (!isPossible) return ret;
	while (!job.empty()) {
		auto curr = job.front();
		job.pop();
		int water = minWall - board[curr.first][curr.second];
		board[curr.first][curr.second] = minWall;
		ret += water;
	}
	return ret;
}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);

	cin >> n >> m;
	for (int i = 0; i < n; i++) {
		string str;
		cin >> str;
		for (int j = 0; j < m; j++) {
			board[i][j] = str[j] - '0';
		}
	}
	int sum = 0;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			sum += bfs(i, j);
		}
	}
	cout << sum;
};