[kuangbin带你飞]之'最小生成树 '专题(未完成)

Posted 2020-11-15 pupil-xj

带飞网址: https://vjudge.net/article/187

专题六：

POJ 1251 Jungle Roads
POJ 1287 Networking
POJ 2031 Building a Space Station
POJ 2421 Constructing Roads
ZOJ 1586 QS Network
POJ 1789 Truck History
POJ 2349 Arctic Network
POJ 1751 Highways
POJ 1258 Agri-Net
POJ 3026 Borg Maze
POJ 1679 The Unique MST
√ HDU 1233 还是畅通工程
√ HDU 1301 Jungle Roads
√ HDU 1875 畅通工程再续

// hdu 1301

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<algorithm>
 4 using namespace std;
 5 
 6 int n;
 7 int p[300];
 8 
 9 struct node {
10     char x, y;
11     int len;
12 } edge[100];
13 
14 int cmp(node a, node b) { return a.len < b.len; }
15 int find(int x) { return p[x] == x ? x : p[x] = find(p[x]); }
16 
17 int main() {
18     while(scanf("%d", &n) == 1 && n) {
19         char s, e;
20         int m, v, k, ans;
21         k = 0;
22         ans = 0;
23         for(int i = 0; i != 300; ++i) { p[i] = i; }
24 
25         for(int i = 0; i != n-1; ++i) {
26             getchar();
27             scanf("%c%d", &s, &m);
28             for(int j = 0; j != m; ++j) {
29                 getchar();
30                 scanf("%c%d", &e, &v);
31                 edge[k].x = s;
32                 edge[k].y = e;
33                 edge[k].len = v;
34                 k++;
35             }
36         }
37         sort(edge, edge+k, cmp);
38         for(int i = 0; i != k; ++i) {
39             int x = find(edge[i].x);
40             int y = find(edge[i].y);
41             if(x != y) {
42                 ans += edge[i].len;
43                 p[x] = y;
44             }
45         }
46         printf("%d
", ans);
47     }
48     return 0;
49 }

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// hdu 1233 

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 using namespace std;
 5 #define MAX 110
 6 struct p{
 7     int start, end;
 8     int weight;
 9 }s[5000];
10 
11 int f[MAX];
12 
13 int cmp(const p & a, const p & b){
14     return a.weight < b.weight;
15 }
16 
17 int find(int x){
18     int r = x, tmp;
19     if(x == f[x]){
20         return x;
21     }
22     while(r != f[r]){
23         r = f[r];
24     }
25     while(x != r){
26         tmp = f[x];
27         f[x] = r;
28         x = tmp;
29     }
30     return r;
31 }
32 
33 int main()
34 {
35     int n, m;
36     while(cin >> n){
37         if(n == 0)break;
38         m = n*(n-1)/2;
39         for(int i = 0; i != m; ++i){
40             scanf("%d%d%d", &s[i].start, &s[i].end, &s[i].weight);
41         }
42         for(int i = 1; i <= n; ++i){
43             f[i] = i;
44         }
45         sort(s, s+m, cmp);
46         int sum = 0;
47         int k = 1;
48         int ans = 0;
49         while(k < n){
50             int i = find(s[ans].start);
51             int j = find(s[ans].end);
52             if(i != j){
53                 f[j] = i;
54                 sum += s[ans].weight;
55                 k++;
56             }
57             ++ans;
58         }
59         printf("%d
", sum);
60     }
61     return 0;
62 }

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// hdu 1875

 1 #include<cstdio>
 2 #include<cmath>
 3 
 4 const double INF = 100005.0;
 5 
 6 struct island {
 7     int x, y;
 8 } p[105];
 9 
10 int n;
11 
12 double getdis(int a, int b) {
13     int x = p[a].x - p[b].x;
14     int y = p[a].y - p[b].y;
15     return sqrt((double)(x*x + y*y));
16 }
17 
18 double dis[105];
19 int vis[105];
20 void prim() {
21     double sum = 0.0;
22     int cnt = 1;
23     for(int i = 0; i != n; ++i) {
24         dis[i] = getdis(0, i);
25         if(dis[i] < 10.0 || dis[i] > 1000.0) dis[i] = INF;
26         vis[i] = 0;
27     }
28     vis[0] = 1;
29     for(int i = 0; i != n-1; ++i) {
30         double minn = INF;
31         int t = -1;
32         for(int j = 0; j != n; ++j) {
33             if(!vis[j] && dis[j] < minn) {
34                 minn = dis[j];
35                 t = j;
36             }
37         }
38         if(t == -1) break;
39         vis[t] = 1;
40         cnt++;
41         sum += minn;
42         for(int j = 0; j != n; ++j) {
43             if(!vis[j] && dis[j] > getdis(t, j) && getdis(t, j) >= 10.0 && getdis(t, j) <= 1000.0) {
44                 dis[j] = getdis(t, j);
45             }
46         }
47     }
48     if(cnt != n) printf("oh!
");
49     else printf("%.1lf
", sum*100.0);
50 }
51 
52 int main() {
53     int T;
54     scanf("%d", &T);
55     while(T--) {
56         scanf("%d", &n);
57         for(int i = 0; i != n; ++i) {
58             scanf("%d%d", &p[i].x, &p[i].y);
59         }
60         prim();
61     }
62     return 0;
63 }

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