POJ 3662 Telephone Lines(二分+最短路)

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　　最小化第K大值。　　　　

　　让我怀疑人生的一题目，我有这么笨？

 #include <cstdio>
 #include <queue>
 #include <cstring>
 #include <vector>
 #include <functional>
 using namespace std;
 #define maxv 1010
 #define maxl 1000000
 struct edge
 {
     int to, cost;
     edge(){}
     edge(int to, int cost) : to(to), cost(cost){}
 };
 typedef pair<int, int> P;
 vector<edge> G[maxv];
 int d[maxv];
 int V, E;
 int dij(int s, int x) {
     priority_queue<P, vector<P>, greater<P> > que;
     memset(d, 0X3f, V*sizeof(int));
     d[s] = ;
     que.push(P(, s));
     while (!que.empty()) {
        P p = que.top(); que.pop();
         int v = p.second;
         if (d[v] < p.first) continue;
         for (int i = ; i < G[v].size(); ++i)
         {
             edge e = G[v][i];
             int new_d = d[v] + (e.cost >= x ?  : );
             if (d[e.to] > new_d)
             {
                 d[e.to] = new_d;
                 que.push(P(d[e.to], e.to));
             }
         }
     }
     return d[V-];
 }
 int main(void) {
     freopen("in.txt", "r", stdin);
     freopen("out.txt", "w", stdout);
     int K;
     scanf("%d%d%d", &V, &E, &K);
     for (int i = ; i < E; ++i) {
         int A, B, L;
         scanf("%d%d%d", &A, &B, &L);
         --A, --B;
         G[A].push_back(edge(B,L));
         G[B].push_back(edge(A,L));
     }
     int l = , u = maxl+;
     for (;(u-l) > ;) {
         int m = (u+l) >> ;
         if (dij(, m) > K) {
             l = m;
         } else {
             u = m;
         }
     }
     printf("%d\n", (l>maxl ? - : l));
     return ;
 }