[POJ2377]Bad Cowtractors(最大生成树，Kruskal)

题目链接：http://poj.org/problem?id=2377

于是就找了一道最大生成树的AC了一下，注意不连通的情况啊，WA了一次。

 /*
 ━━━━━┒ギリギリ♂ eye！
 ┓┏┓┏┓┃キリキリ♂ mind！
 ┛┗┛┗┛┃＼○／
 ┓┏┓┏┓┃ /
 ┛┗┛┗┛┃ノ)
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┃┃┃┃┃┃
 ┻┻┻┻┻┻
 */
 #include <algorithm>
 #include <iostream>
 #include <iomanip>
 #include <cstring>
 #include <climits>
 #include <complex>
 #include <fstream>
 #include <cassert>
 #include <cstdio>
 #include <bitset>
 #include <vector>
 #include <deque>
 #include <queue>
 #include <stack>
 #include <ctime>
 #include <set>
 #include <map>
 #include <cmath>
 using namespace std;
 #define fr first
 #define sc second
 #define cl clear
 #define BUG puts("here!!!")
 #define W(a) while(a--)
 #define pb(a) push_back(a)
 #define Rint(a) scanf("%d", &a)
 #define Rll(a) scanf("%lld", &a)
 #define Rs(a) scanf("%s", a)
 #define Cin(a) cin >> a
 #define FRead() freopen("in", "r", stdin)
 #define FWrite() freopen("out", "w", stdout)
 #define Rep(i, len) for(int i = 0; i < (len); i++)
 #define For(i, a, len) for(int i = (a); i < (len); i++)
 #define Cls(a) memset((a), 0, sizeof(a))
 #define Clr(a, x) memset((a), (x), sizeof(a))
 #define Full(a) memset((a), 0x7f7f, sizeof(a))
 #define lrt rt << 1
 #define rrt rt << 1 | 1
 #define pi 3.14159265359
 #define RT return
 #define lowbit(x) x & (-x)
 #define onenum(x) __builtin_popcount(x)
 typedef long long LL;
 typedef long double LD;
 typedef unsigned long long ULL;
 typedef pair<int, int> pii;
 typedef pair<string, int> psi;
 typedef map<string, int> msi;
 typedef vector<int> vi;
 typedef vector<LL> vl;
 typedef vector<vl> vvl;
 typedef vector<bool> vb;

 typedef struct Edge {
     int u, v, w;
     Edge() {}
     Edge(int uu, int vv, int ww) : u(uu), v(vv), w(ww) {}
 }Edge;
 const int maxn = ;
 const int maxm = ;
 int n, m;
 int pre[maxn];
 Edge edge[maxm];

 bool cmp(Edge a, Edge b) {
     RT a.w > b.w;
 }

 int find(int x) {
     return x == pre[x] ? x : pre[x] = find(pre[x]);
 }

 int unite(int x, int y) {
     int fx = find(x);
     int fy = find(y);
     if(fx != fy) {
         pre[fy] = fx;
         return ;
     }
     return ;
 }

 int main() {
     // FRead();
     int u, v, c;
     while(~Rint(n) && ~Rint(m)) {
         Rep(i, n+) pre[i] = i;
         Rep(i, m) {
             Rint(u); Rint(v); Rint(c);
             edge[i] = Edge(u, v, c);
         }
         sort(edge, edge+m, cmp);
         int ret = ;
         Rep(i, m) {
             if(unite(edge[i].u, edge[i].v)) {
                 ret += edge[i].w;
             }
         }
         int flag = ;
         For(i, , n+) {
             if(pre[i] == i) flag++;
             if(flag > ) break;
         }
         if(flag > ) printf("-1\n");
         else printf("%d\n", ret);
     }
     RT ;
 }