[백준 14503번 C/C++] 로봇 청소기

[백준 14503번 C/C++] 로봇 청소기

https://www.acmicpc.net/problem/14503

해결전략

구현

정답코드

#include <iostream>
#include <vector>
using namespace std;
 
int dirY[4] = { -1, 0, 1, 0 };
int dirX[4] = { 0, 1, 0, -1 };
 
int n, m;
int currY, currX, currDir;
vector<vector<int>> v;
int answer; // 청소하는 칸의 개수
 
 
bool Move(int y, int x, int dir)
{
	// 4 방향 체크 
	for (int i = 0; i < 4; i++) {
		int nextDir = (dir + 3 - i) % 4; // 왼쪽으로 돌기
		int ny = y + dirY[nextDir];
		int nx = x + dirX[nextDir];
 
		if (ny < 0 || n <= ny || nx < 0 || m <= nx) continue;
 
		if (v[ny][nx] == 0){
			v[ny][nx] = -1;
			answer++;
			currY = ny, currX = nx, currDir = nextDir;
			return true;
		}
	}
 
	// 후진
	if (dir == 0 && y + 1 < n && v[y + 1][x] != 1){
		currY = y + 1, currX = x, currDir = dir;
		return true;
	}
	else if (dir == 1 && 0 <= x - 1 && v[y][x - 1] != 1){
		currY = y, currX = x - 1, currDir = dir;
		return true;
	}
	else if (dir == 2 && 0 <= y - 1 && v[y - 1][x] != 1){
		currY = y - 1, currX = x, currDir = dir;
		return true;
	}
	else if (dir == 3 && x + 1 < m && v[y][x + 1] != 1){
		currY = y, currX = x + 1, currDir = dir;
		return true;
	}
 
	return false;
}
 
void Clean(int y, int x, int dir)
{
	//cout << y << ", " << x << ", dir = " << dir << "\n";
 
	if (Move(y, x, dir)){
 
		Clean(currY, currX, currDir);
	}
}
 
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
 
	cin >> n >> m;
	v.resize(n, vector<int>(m));
	cin >> currY >> currX >> currDir;
	for (int y = 0; y < n; y++){
		for (int x = 0; x < m; x++) {
			cin >> v[y][x];
		}
	}
 
	// 시작 칸이 아직 청소되지 않은 경우, 시작 칸을 청소
	if (v[currY][currX] == 0) {
		v[currY][currX] = -1;
		answer++;
	}
 
	Clean(currY, currX, currDir);
 
	cout << answer;
 
	return 0;
}

해결전략

처음 실수한 부분

	for (int i = dir; i < dir + 4; i++){
		int ny = y + dirY[i % 4];
		int nx = x + dirX[i % 4];
 
		if (ny < 0 || n <= ny || nx < 0 || m <= nx) continue;
 
		if (v[ny][nx] == 0){
			v[ny][nx] = -1;
			answer++;
			currY = ny, currX = nx, currDir = (i % 4);
			return true;
		}
	}

고친 코드

	for (int i = 0; i < 4; i++) {
		int nextDir = (dir + 3 - i) % 4; // 왼쪽으로 돌기
		int ny = y + dirY[nextDir];
		int nx = x + dirX[nextDir];
 
		if (ny < 0 || n <= ny || nx < 0 || m <= nx) continue;
 
		if (v[ny][nx] == 0){
			v[ny][nx] = -1;
			answer++;
			currY = ny, currX = nx, currDir = nextDir;
			return true;
		}
	}

Ver.1

	if (dir == 0 && y + 1 < n && v[y + 1][x] != 1){
		currY = y + 1, currX = x, currDir = dir;
		return true;
	}
	else if (dir == 1 && 0 <= x - 1 && v[y][x - 1] != 1){
		currY = y, currX = x - 1, currDir = dir;
		return true;
	}
	else if (dir == 2 && 0 <= y - 1 && v[y - 1][x] != 1){
		currY = y - 1, currX = x, currDir = dir;
		return true;
	}
	else if (dir == 3 && x + 1 < m && v[y][x + 1] != 1){
		currY = y, currX = x + 1, currDir = dir;
		return true;
	}

Ver.2

  	int backDir = (dir + 2) % 4;
    int ny = y + dirY[backDir];
    int nx = x + dirX[backDir];
 
    if (ny >= 0 && ny < n && nx >= 0 && nx < m && v[ny][nx] != 1) {
        currY = ny;
        currX = nx;
        currDir = dir;
        return true;
    }