[POJ1679] The Unique MST sub-niche into a tree

Title Link: http://poj.org/problem?id=1679

Give you a graph of connectivity, asking you whether the minimum spanning tree of this graph is unique.

If the minimum spanning tree is unique, that is, the spanning tree communicates the weights and uniqueness of all nodes. If not unique, then there is another minimum spanning tree so that the weights are equal to the weights of the previous minimum spanning tree.

Another thought, that is, the weight of the sub-niche tree is the same as the minimum spanning tree weights, then the problem becomes the second niche into a tree weight.

I chose to first find the smallest spanning tree and save the edges that are used on the tree. Then take each of the edges you use, and then find the minimum spanning tree. The minimum spanning tree is not unique if the selected edge weights of the spanning tree that do not contain the currently deleted edges are the same as the selected edge weights of the smallest spanning tree.

Code:

1#include <algorithm>2#include <iostream>3#include <iomanip>4#include <cstring>5#include <climits>6#include <complex>7#include <fstream>8#include <cassert>9#include <cstdio>Ten#include <bitset> One#include <vector> A#include <deque> -#include <queue> -#include <stack> the#include <ctime> -#include <Set> -#include <map> -#include <cmath> +  - using namespacestd; +  AtypedefstructNode { at     intu; -     intv; -     intW; - }node; -  - BOOLCMP (node n1, node N2) { in     returnN1.W <N2.W; - } to  + Const intMAXN =111; -Node node[6666]; the intVIS[MAXN]; * intN, M, U, V, W; $ intPRE[MAXN];Panax Notoginseng intcnt, dig, flag, ans; -  the voidinit () { +      for(inti =0; I <= MAXN; i++) { APre[i] =i; the     } + } -  $ intFindintx) { $     returnx = = Pre[x]? X:PRE[X] =find (Pre[x]); - } -  the voidUniteintXinty) { -x =find (x);Wuyiy =find (y); the     if(x! = y) Pre[y] =x; - } Wu  - intMain () { About     //freopen ("in", "R", stdin); $     intT; -scanf"%d", &T); -      while(t--) { - init (); Amemset (Vis,0,sizeof(Vis)); +memset (node,0,sizeof(node)); theDig =0; -CNT =0; $Flag =0; thescanf"%d%d", &n, &m); the          for(inti =0; I < m; i++) { thescanf" %d%d%d", &u, &v, &W); theNODE[I].U =u; -NODE[I].V =v; inNODE[I].W =W; the         } theSort (node, node+m, CMP); About          for(inti =0; I < m && CNT < n; i++) { the             if(Find (node[i].u)! =find (NODE[I].V)) { the Unite (NODE[I].U, NODE[I].V); thevis[cnt++] =i; +Dig + =NODE[I].W; -             } the         }BayiAns =dig; the  the          for(inti =1; I < n; i++) { - init (); -CNT = n-1; theDig =0; the              for(intj =0; J < m && CNT; J + +) { the                 if(Vis[i]! = J && Find (node[j].u)! =find (NODE[J].V)) { the Unite (NODE[J].U, NODE[J].V); -Dig + =NODE[J].W; thecnt--; the                 } the             }94             if(CNT = =0&& Dig = =ans) { theFlag =1; the                  Break; the             }98         } About  -         if(flag) printf ("Not unique!\n");101         Elseprintf"%d\n", ans);102     }103}

[POJ1679] The Unique MST sub-niche into a tree