Treasure Island Adventure
Diaoyu Islands is composed of a main island and several affiliated islands, small hum decided to go to the Diaoyu Islands adventure. The following two-dimensional matrix 10 * 10 is an aerial map of the Diaoyu Islands. FIG digital elevation showing, 0 marine, land represents 1 to 9. Small hum of the aircraft will land at (6,8), and now need to calculate the area of a small island where the hum landed (ie, the number of grid).
A method (BFS using a queue)
#include <stdio.h>
struct note{
int x;
int y;
};
int main()
{
struct note que[2501];
int head=1,tail=1;
int a[51][51],book[51][51];
int n,m,startx,starty,tx,ty,k,i,j;
int next[4][2]={{0,1},{1,0},{0,-1},{-1,0}};
scanf("%d %d %d %d",&n,&m,&startx,&starty);
for(i=1;i<=n;i++)
for(j=1;j<=m;j++)
scanf("%d",&a[i][j]);
que[tail].x=startx;
que[tail].y=starty;
tail++;
book[startx][starty]=1;
int sum=1;
while(head<tail)
{
for(k=0;k<4;k++)
{
tx=que[head].x+next[k][0];
ty=que[head].y+next[k][1];
if(tx<1||tx>n||ty<1||ty>m)
continue;
if(book[tx][ty]==0&&a[tx][ty]>0)
{
book[tx][ty]=1;
que[tail].x=tx;
que[tail].y=ty;
sum++;
tail++;
}
}
head++;
}
printf("%d",sum);
return 0;
}
Method II (DFS):
#include <stdio.h>
int book[51][51],a[51][51];
int m,n,sum ;
void DFS(int x,int y )
{
int k,tx,ty;
int next[4][2]={{0,1},{1,0},{0,-1},{-1,0}};
for(k=0;k<4;k++)
{
tx=x+next[k][0];
ty=y+next[k][1];
if(tx<1||ty<1||tx>n||ty>m)
continue;
if(book[tx][ty]==0&&a[tx][ty]>0)
{
sum++;
book[tx][ty]=1;
DFS(tx,ty);
}
}
}
int main()
{
int startx,starty,i,j;
scanf("%d %d %d %d",&n,&m,&startx,&starty);
for(i=1;i<=n;i++)
for(j=1;j<=m;j++)
scanf("%d",&a[i][j]);
book[startx][starty]=1;
sum=1;
DFS(startx,starty);
printf("%d",sum);
return 0;
}
```
