UVa 572 油田（DFS求连通块）

https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=513

终于开始接触图了，恩，开始接触DFS了，这道题就是求连通分量，比较简单。

#include<iostream>
#include<cstring>
using namespace std;

int m, n;                                               //记录连通块的数量
char a[10000][10000];
int  b[10000][10000];

void DFS(int i, int j, int count)
{
    if (i < 0 || i >= m || j < 0 || j >= n) return;     //在递归时出界的情况
        if(b[i][j]>0 || a[i][j]!='@')  return;
    b[i][j] = count;
    for (int p = -1; p <= 1; p++)
    {
        for (int q = -1; q <= 1; q++)
        {
            if (p != 0||q != 0)  DFS(i + p, j + q, count);
        }
    }
}

int main()
{
    while (cin >> m >> n && m && n)
    {
        for (int i = 0; i < m; i++)
            scanf("%s", &a[i]);
        int count = 0;
        memset(b, 0, sizeof(b));
        for (int i = 0; i < m; i++)
        {
            for (int j = 0; j < n; j++)
            {
                if (b[i][j] == 0 && a[i][j]=='@') DFS(i, j, ++count);
            }
        }
        cout << count << endl;
    }
    return 0;
}

2016-12-03  07:49:56