poj 1979 Red and Black 递归实现

Red and Black

Time Limit: 1000MS Memory Limit: 30000KTotal Submissions: 20075 Accepted: 10737

Description

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) 
The end of the input is indicated by a line consisting of two zeros. 

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

4559613

Source CodeProblem: 1979Memory: 172KTime: 0MSLanguage: CResult: AcceptedSource Code#include <stdio.h>int W, H;char data[21][21];int f(int i, int j){if(i < 0 || i >= H || j < 0 || j >= W)return 0;if(data[i][j]=='#')return 0;else{data[i][j]='#';return 1+f(i-1,j)+f(i+1, j)+f(i,j-1)+f(i,j+1);}}int main(){//freopen("input.txt","r",stdin);int i, j;while(scanf("%d%d", &W, &H) && W != 0 && H != 0){for(i=0; i < H; i++)scanf("%s", data[i]);for(i=0; i < H; i++)for(j=0; j < W; j++)if(data[i][j]=='@')printf("%d\n", f(i ,j));}return 0;}