ZOJ Problem Set - 2165 Red and Black
There is a rectangular room, covered with square tiles. Each tile is colored either red or black. A man is standing on a black tile. From a tile, he can move to one of four adjacent tiles. But he can't move on red tiles, he can move only on black tiles.
Write a program to count the number of black tiles which he can reach by repeating the moves described above.
Input
The input consists of multiple data sets. A data set starts with a line containing two positive integers W and H; W and H are the numbers of tiles in the x- and y- directions, respectively. W and H are not more than 20.
There are H more lines in the data set, each of which includes W characters. Each character represents the color of a tile as follows.
- '.' - a black tile
- '#' - a red tile
- '@' - a man on a black tile(appears exactly once in a data set)
Output
For each data set, your program should output a line which contains the number of tiles he can reach from the initial tile (including itself).
Sample Input
6 9
....#.
.....#
......
......
......
......
......
#@...#
.#..#.
11 9
.#.........
.#.#######.
.#.#.....#.
.#.#.###.#.
.#.#..@#.#.
.#.#####.#.
.#.......#.
.#########.
...........
11 6
..#..#..#..
..#..#..#..
..#..#..###
..#..#..#@.
..#..#..#..
..#..#..#..
7 7
..#.#..
..#.#..
###.###
...@...
###.###
..#.#..
..#.#..
0 0
Sample Output
45
59
6
13
#include<iostream> #include<stdio.h> #include<string.h> #define MAX 30 using namespace std; char map[MAX][MAX]; int count=0; int w,h; int dir[4][2]={{0,-1},{-1,0},{0,1},{1,0}}; void dfs(int r,int c) { // cout<<"r: "<<r<<" c: "<<c<<endl; //getchar(); if(r<=0||c<=0||r>h||c>w) { return; } map[r][c]='#'; for(int i=0;i<4;i++) { if(map[r+dir[i][0]][c+dir[i][1]]=='.') { // map[r+dir[i][0]][c+dir[i][1]]='#'; count++; dfs(r+dir[i][0],c+dir[i][1]); // map[r+dir[i][0]][c+dir[i][1]]='.'; } } } int main() { while(cin>>w>>h) { if(w==0||h==0)break; int sr,sc; count=0; memset(map,0,sizeof(map)); for(int i=1;i<=h;i++) { for(int j=1;j<=w;j++) { cin>>map[i][j]; if(map[i][j]=='@') { sr=i;sc=j; } } } map[sr][sc]='#'; //cout<<"Mark #1"<<endl; dfs(sr,sc); cout<<count+1<<endl; } }