AHU-61 Lake Counting (并查集）

这里写图片描述

简单并查集

Code

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 const int MAXN = 10000 + 10;
 4 const int dx[] = {1, -1, 0, 0, 1, -1, 1, -1};
 5 const int dy[] = {0, 0, 1, -1, 1, -1, -1, 1};
 6 int node[MAXN], pre[MAXN];
 7 
 8 int find(int x) {
 9     return pre[x] == x ? x : pre[x] = find(pre[x]);
10 }
11 
12 void join(int x, int y) {
13     int xx = find(x);
14     int yy = find(y);
15     if (xx != yy) {
16         pre[yy] = xx;
17     }
18 }
19 
20 int main() {
21     int n, m, z;
22     while(~scanf("%d%d", &n, &m)) {
23         getchar();
24         char ch;
25         for (int i = 0; i < n; ++i) {
26             for (int j = 0; j <= m; ++j) { //j多循环一次读换行
27                 scanf("%c", &ch);
28                 z = i * m + j;
29                 if (ch == '.') node[z] = 0;
30                 else if (ch == 'W') node[z] = 1;
31                 pre[z] = z;
32             }
33         }
34         for (int i = 0; i < n*m; ++i) {
35             if (node[i] == 0) continue;
36             int x = i / m, y = i % m;
37             for (int j = 0; j < 8; ++j) {
38                 int nx = x + dx[j], ny = y + dy[j];
39                 if (nx < 0 || nx >= n || ny < 0 || ny >= m) continue;
40                 int nz = nx * m + ny;
41                 if (node[nz] == 1)
42                     join(i, nz);
43             }
44         }
45         set<int> root;
46         for (int i = 0; i < n*m; ++i) {
47             if (node[i] == 0) continue;
48             int nroot = find(i);
49             root.insert(nroot);
50         }
51         printf("%d\n", root.size());
52     }
53 
54     return 0;
55 }

 

 
posted @ 2017-01-23 14:28  Robin!  阅读(201)  评论(0)  编辑  收藏  举报