hdu 1856 More is better （并查集）

　　水题。离散化，然后求最大集合元素个数。

　　忘记压缩路径了，tle了很久。- -

代码如下：

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 #include <algorithm>
 5 #include <map>
 6 
 7 using namespace std;
 8 
 9 const int N = 222222;
10 map<int, int> id;
11 
12 struct MFS {
13     int fa[N], sz[N], mxsz;
14     void init() {
15         for (int i = 0; i < N; i++) fa[i] = i, sz[i] = 1;
16         mxsz = 1;
17     }
18     int find(int x) { return fa[x] = x == fa[x] ? x : find(fa[x]);}
19     void merge(int x, int y) {
20         int fx = find(x), fy = find(y);
21         if (fx == fy) return ;
22         fa[fx] = fy;
23         sz[fy] += sz[fx];
24         mxsz = max(mxsz, sz[fy]);
25     }
26 } mfs;
27 
28 int main() {
29     int n, x, y;
30     while (~scanf("%d", &n)) {
31         mfs.init();
32         id.clear();
33         while (n--) {
34             scanf("%d%d", &x, &y);
35             if (id.find(x) == id.end()) id[x] = id.size();
36             if (id.find(y) == id.end()) id[y] = id.size();
37             mfs.merge(id[x], id[y]);
38         }
39         printf("%d\n", mfs.mxsz);
40     }
41     return 0;
42 }

View Code

 1 #include <cstdio>
 2 #include <iostream>
 3 #include <algorithm>
 4 #include <cstring>
 5 
 6 using namespace std;
 7 
 8 const int N = 222222;
 9 const int M = 11111111;
10 
11 struct MFS {
12     int fa[N], sz[N], mxsz;
13     void init() { mxsz = 1;}
14     int find(int x) { return fa[x] = fa[x] == x ? x : find(fa[x]);}
15     void merge(int x, int y) {
16         int fx = find(x);
17         int fy = find(y);
18         if (fx == fy) return ;
19         if (sz[fx] > sz[fy]) {
20             fa[fx] = fy;
21             sz[fy] += sz[fx];
22             mxsz = max(mxsz, sz[fy]);
23         } else {
24             fa[fy] = fx;
25             sz[fx] += sz[fy];
26             mxsz = max(mxsz, sz[fx]);
27         }
28     }
29 } mfs;
30 
31 inline bool isdg(char x) { return '0' <= x && x <= '9';} 
32 void scan(int &x) {
33     char ch;
34     while (!isdg(ch = getchar())) ;
35     x = ch - '0';
36     while (isdg(ch = getchar())) x = x * 10 + ch - '0';
37 }
38 
39 int id[M], rx[N], x[N >> 1], y[N >> 1];
40 
41 int main() {
42     int n;
43     while (~scanf("%d", &n)) {
44         mfs.init();
45         for (int i = 0; i < n; i++) {
46             //scanf("%d%d", &x[i], &y[i]);
47             scan(x[i]), scan(y[i]);
48             rx[i << 1] = x[i];
49             rx[i << 1 | 1] = y[i];
50         }
51         sort(rx, rx + (n << 1));
52         int m = unique(rx, rx + (n << 1)) - rx;
53         for (int i = 0; i < m; i++) id[rx[i]] = i, mfs.sz[i] = 1, mfs.fa[i] = i;
54         for (int i = 0; i < n; i++) {
55             mfs.merge(id[x[i]], id[y[i]]);
56         }
57         printf("%d\n", mfs.mxsz);
58     }
59     return 0;
60 }

View Code

——written by Lyon

posted @ 2013-07-22 12:37 LyonLys 阅读(180) 评论(0) 编辑收藏举报

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