B - 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 Write a program to count the number of black tiles which he can reach by repeating the moves described above.
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 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.
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 0Sample Output
45 59 6 13
#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<stdlib.h>
#include<string.h>
using namespace std;
int m,n;//n代表列,m代表行
int cnt;
char mp[100][100];
void dfs(int p,int q){//p是行 q是列
if(mp[p][q]!='.' || p<0 || q<0 || p>=m||q>=n){
return ;
}else{
cnt++;
mp[p][q]='#';
dfs(p-1,q);
dfs(p,q+1);
dfs(p+1,q);
dfs(p,q-1);
}
}
int main(){
int i,j;
while(scanf("%d%d",&n,&m)!=EOF){
cnt=0;
memset(mp,0,sizeof(mp));
if(n==0 && m==0){
break;
}
for(i=0;i<m;i++){
for(j=0;j<n;j++){
cin>>mp[i][j];
}
//getchar();
}
for(i=0;i<m;i++){
for(j=0;j<n;j++){
if(mp[i][j]=='@'){
mp[i][j]='.';
dfs(i,j);
}
}
}
cout<<cnt<<endl;
}
return 0;
}
#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
using namespace std;
char mp[100][100];
int cnt;
int n,m;
void f(char mp[100][100],int x,int y){
mp[x][y]='#';
if(x+1<m && mp[x+1][y]=='.'){
cnt++;
f(mp,x+1,y);
}
if(x-1>-1 && mp[x-1][y]=='.'){
cnt++;
f(mp,x-1,y);
}
if(y+1<n && mp[x][y+1]=='.'){
cnt++;
f(mp,x,y+1);
}
if(y-1>-1 && mp[x][y-1]=='.'){
cnt++;
f(mp,x,y-1);
}
}
int main(){
int i,j;
while(scanf("%d%d",&n,&m)!=EOF){
if(n==0 ||m==0)
break;
for(i=0;i<m;i++){
scanf("%s",&mp[i]);
}
for(i=0;i<m;i++){
for(j=0;j<n;j++){
if(mp[i][j]=='@'){
cnt=1;
f(mp,i,j);
printf("%d\n",cnt);
}
}
}
}
}
自己的代码
经典的搜索题目,深度优先搜索,其描述如下:
void dfs()
{
for(所有的邻接节点)
{
if(节点没有被遍历)
{
标记此节点;
dfs(此节点);
}
}
}
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<iostream>
#include<algorithm>
#include<math.h>
using namespace std;
char mp[21][21];
int v[21][21];
int m,n;
int cnt=0;
int dir[4][2]={{0,1},{0,-1},{-1,0},{1,0}};
//int dir[4][2]={{1,0},{-1,0},{0,1},{0,-1}};
void dfs(int w,int e)
{
for(int i=0;i<4;i++)
{
int ww=w+dir[i][0];
int ee=e+dir[i][1];
// cout<<"ww* "<<ww<<"ee* "<<ee<<endl;
if(mp[ww][ee]=='.'&&ww>=0&&ww<n&&ee>=0&&ee<m)
{
cnt++;
v[ww][ee]=1;
mp[ww][ee]='#';
// cout<<"ww= "<<ww<<"ee= "<<ee<<endl;
dfs(ww,ee);
}
}
}
int main()
{
while(scanf("%d%d",&m,&n)!=EOF)
{
int x,y;
memset(mp,0,sizeof(mp));
memset(v,0,sizeof(v));
if(m==0 ||n==0)
break;
for(int i=0;i<n;i++)
{
for(int j=0;j<m;j++)
{
cin>>mp[i][j];
if(mp[i][j]=='@')
{
x=i;
y=j;
}
}
}
// cout<<"x= "<<x<<"y= "<<y<<endl;
mp[x][y]='#';
cnt=1;
dfs(x,y);
printf("%d\n",cnt);
}
return 0;
}
或者
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<iostream>
#include<algorithm>
#include<math.h>
using namespace std;
char mp[21][21];
int v[21][21];
int m,n;
int cnt=0;
int dir[4][2]={{0,1},{0,-1},{-1,0},{1,0}};
//int dir[4][2]={{1,0},{-1,0},{0,1},{0,-1}};
void dfs(int w,int e)
{
for(int i=0;i<4;i++)
{
int ww=w+dir[i][0];
int ee=e+dir[i][1];
//cout<<"ww* "<<ww<<"ee* "<<ee<<endl;
if(mp[ww][ee]=='.'&&ww>=0&&ww<n&&ee>=0&&ee<m&&v[ww][ee]==0)
{
cnt++;
v[ww][ee]=1;
mp[ww][ee]='#';
// cout<<"ww= "<<ww<<"ee= "<<ee<<endl;
dfs(ww,ee);
}
}
}
int main()
{
while(scanf("%d%d",&m,&n)!=EOF)
{
int x,y;
memset(mp,0,sizeof(mp));
memset(v,0,sizeof(v));
if(m==0 ||n==0)
break;
for(int i=0;i<n;i++)
{
for(int j=0;j<m;j++)
{
cin>>mp[i][j];
if(mp[i][j]=='@')
{
x=i;
y=j;
}
}
}
// cout<<"x= "<<x<<"y= "<<y<<endl;
mp[x][y]='#';
v[x][y]=1;
cnt=1;
dfs(x,y);
printf("%d\n",cnt);
}
return 0;
}