# UVA 572 Oil Deposits
## 題目連結 [UVA 572](https://vjudge.net/problem/UVA-572)
### 題目內容
The GeoSurvComp geologic survey company is responsible for detecting underground oil deposits.
GeoSurvComp works with one large rectangular region of land at a time, and creates a grid that divides the land into numerous square plots. It then analyzes each plot separately, using sensing equipment to determine whether or not the plot contains oil.
A plot containing oil is called a pocket. If two pockets are adjacent, then they are part of the same oil deposit. Oil deposits can be quite large and may contain num
### 輸入限制
The input file contains one or more grids. Each grid begins with a line containing m and n, the number of rows and columns in the grid, separated by a single space. If m = 0 it signals the end of the input;otherwise 1 ≤ m ≤ 100 and 1 ≤ n ≤ 100. Following this are m lines of n characters each (not counting the end-of-line characters). Each character corresponds to one plot, and is either ‘*’, representing the absence of oil, or ‘@’, representing an oil pocket.

### 輸出限制
For each grid, output the number of distinct oil deposits. Two different pockets are part of the same oil deposit if they are adjacent horizontally, vertically, or diagonally. An oil deposit will not contain more than 100 pockets
### 解題思路
這題屬於連通圖，要利用回朔(dfs)來解，先遍歷陣列中每個元素，如果是@就跑dfs，終止條件式超出範圍或是不等於@，要注意的是要把跑過的@都改為*(a[ i ][ j ]=' * ';)。
### 程式碼

#include<bits/stdc++.h>
using namespace std;
char a[105][105];
int n,m;
int dx[8]={1,1,0,-1,-1,-1,0,1};
int dy[8]={0,1,1,1,0,-1,-1,-1};
void dfs(int i,int j){
    if(i<0 || i>n || j<0 || j>m){
	return;
    }
    if(a[i][j]!='@'){
	return;
    }
    a[i][j]='*';
    for(int k=0;k<8;k++){
       dfs(i+dx[k],j+dy[k]);
    }
}
int main(){
    while(cin>>n>>m && n!=0){
	for(int i=0;i<n;i++){
		for(int j=0;j<m;j++){
			cin>>a[i][j];
		}
	}
        int cot=0;
	for(int i=0;i<n;i++){
		for(int j=0;j<m;j++){
        		if(a[i][j]=='@'){
			    dfs(i,j);
                           cot++;
			}
		}
	}
        cout<<cot<<endl;
    }
}

## 測資
### Sample input
1 1
*
3 5
*@*@*
**@**
*@*@*
1 8
@@****@*
5 5
****@
*@@*@
*@**@
@@@*@
@@**@
0 0
### Sample output
0
1
2
2
## 中文題目連結 [zerojudge a129](https://zerojudge.tw/ShowProblem?problemid=c129)