784 - Maze Exploration

思路：從*所在的位置出發，dfs歷遍所有與它聯通的點並將其變爲#

dfs實現關鍵思路在於兩點：

1.哪些點是與當前點聯通的

2.dfs返回條件

代碼如下：

#include<iostream>
using namespace std;

char maze[35][90];
int visit[35][90];
int r;//the row of maze

void DFS(int row, int col) {
	if (row<0 || row>r - 1)return;
	int len =strlen(maze[row]);
	if (col<0 || col>len - 1)return;
	if (visit[row][col]||maze[row][col] == 'X')return;
	
	visit[row][col] = 1;
	if (maze[row][col] == ' '|| maze[row][col] == '*')maze[row][col] = '#';
	for (int i = -1; i <= 1; i++)
		for (int j = -1; j <= 1; j++)
		{
			if (i == 0 && j == 0)continue;
			DFS(row + i, col + j);
		}
}
int main() {
	//FILE*stream;
	//freopen_s(&stream, "C:\\Data\\784Maze.txt", "r", stdin);

	int num;
	scanf_s("%d", &num);
	char c = getchar();

	while (num--) {
		//read in maze
		r = 0;
		while (1) {
			gets_s(maze[r]);
			if (maze[r][0] == '_')break;
			r++;
		}

		//find *
		int x, y;
		for (int i = 0; i < r; i++)
			for (int j = 0; j < strlen(maze[i]); j++)
				if (maze[i][j] == '*') {
					x = i; y = j; break;
				}

		memset(visit, 0, sizeof(visit));
		DFS(x, y);

		//output
		for (int i = 0; i <= r; i++)
			printf_s("%s\n", maze[i],90);
				
	}
}