P2330-[SCOI2005]繁忙的都市 

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 #define pb push_back
 4 #define _for(i,a,b) for(int i = (a);i < (b);i ++)
 5 #define INF 100000003
 6 #define ll long long
 7 inline ll read()
 8 {
 9     ll ans = 0;
10     char ch = getchar(), last = ' ';
11     while(!isdigit(ch)) last = ch, ch = getchar();
12     while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();
13     if(last == '-') ans = -ans;
14     return ans;
15 }
16 inline void write(ll x)
17 {
18     if(x < 0) x = -x, putchar('-');
19     if(x >= 10) write(x / 10);
20     putchar(x % 10 + '0');
21 }
22 int n;
23 int mincost[303];
24 bool used[303];
25 struct edge
26 {
27     int to,cost;
28 };
29 vector<edge> G[303];
30 int V,E;
31 int maxx = 0;
32 int minn = INF;
33 int MST(int K)
34 {
35     _for(i,1,V+1)
36     {
37         mincost[i] = INF;
38         used[i] = false;
39     }
40 
41     mincost[1] = 0;
42     int res = 0;
43 
44     while(1)
45     {
46         int v = -1;
47         _for(u,1,V+1)
48         if(!used[u] && (v==-1 || mincost[u] < mincost[v]))
49             v = u;
50         
51         if(v==-1) break;
52         used[v] = true;
53         res += mincost[v];
54 
55         _for(u,0,G[v].size())
56             if(G[v][u].cost<=K)
57                 mincost[G[v][u].to] = min(mincost[G[v][u].to],G[v][u].cost);
58     }
59     return res;
60 }
61 bool C(int d)
62 {
63     if(MST(d)>=INF)
64         return false;
65     return true;
66 }
67 int solve()
68 {
69     int lb = minn,ub = maxx;
70     while(ub - lb > 1)
71     {
72         int mid =  lb+(ub-lb)/2;
73         if(C(mid)) ub = mid;
74         else lb = mid;
75     }
76 
77     if(!C(lb))
78         return lb+1;
79     return lb;
80 }
81 
82 int main()
83 {
84     V = read(),E = read();
85     _for(i,0,E)
86     {
87         int a,b,c;
88         a = read(),b = read(), c = read();
89         G[a].push_back({b,c});
90         G[b].push_back({a,c});
91         maxx = max(maxx,c);
92         minn = min(minn,c);
93     }
94 
95     int rnt = solve();
96     printf("%d %d",V-1,rnt);
97     return 0;
98 }

 

posted @ 2019-09-15 16:18  Asurudo  阅读(126)  评论(0)    收藏  举报