[JOBDU] Topic 1545: Strange connected diagrams

Title Description:

A non-weighted graph is known to find the smallest integer k. To make the only use value less than or equal to K, node 1 can be connected to node N.

Input:

The input contains multiple sets of test cases, each set of test cases starting with an integer n (1 <= n <= 10000), M (1 <= m <= 100000), representing the number of vertices, and the number of edges, of the weighted graph.
Next to the M line, the information describing the top of the graph, including three integers, a (1 <= a <= N), B (1 <= b <= N), C (1 <= C <= 1000000), represents the non-forward edge of the connection vertex A and vertex B, with a weight of c.

Output:

The output is an integer k, and output-1 if an integer is not found to satisfy the condition.

Sample input:

Sample output:

35-1

Start to see the topic feel good complex, first think of is a binary search, but even the two-point search, the complexity is too high. In fact, this is the test and check set, by the length of the side of the order, the first time found that N and 1 connected to the edge is the K. Because it's already been sorted.

1#include <iostream>2#include <vector>3#include <algorithm>4#include <cstdio>5 using namespacestd;6  7 structedge_t {8     intA, B;9     intDist;Ten }; One   A intN, M; -Vector<edge_t>edges; -vector<int>father; the   - intFindfather (intx) { -      while(X! =Father[x]) { -x =Father[x]; +     } -     returnx; + } A   at BOOLcmpConstedge_t &a,ConstEdge_t &b) { -     returnA.dist <b.dist; - } -   - voidinit () { -      for(inti =0; I < father.size (); ++i) inFather[i] =i; - sort (Edges.begin (), Edges.end (), CMP); to } +   - voidsolve () { the      for(inti =0; I < m; ++i) { *         intFA =Findfather (EDGES[I].A); $         intFB =Findfather (edges[i].b);Panax Notoginseng         if(FA < FB) FATHER[FB] =FA; -         ElseFATHER[FA] =FB; the         if(Findfather (n) = =1) { +cout << edges[i].dist <<Endl; A             return; the         } +     } -cout <<"-1"<<Endl; $ } $   - intMain () { -      while(SCANF ("%d%d", &n, &m)! =EOF) { theFather.resize (n +1); - edges.resize (m);Wuyi          for(inti =0; I < m; ++i) { thescanf" %d%d%d", &AMP;EDGES[I].A, &edges[i].b, &edges[i].dist); -         } Wu init (); - solve (); About     } $     return 0; - } - /************************************************************** - problem:1545 A user:hupo250 + language:c++ the result:accepted - time:640 Ms $ memory:2248 KB the ****************************************************************/

[JOBDU] Topic 1545: Strange connected diagrams