UVa 11747 - Heavy Cycle Edges

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题目：计算最小生成树的kruskal算法，有两种途径，方法一是我们常用的不断的把边加到目标集合上。

方法二是从图中不断的删边，最后剩下的就是所求集合。

分析：最小生成树。利用kruskal算法的方法一，求剩下的边就是删掉的边，即为所求。

注意：数组别开小了，特别是并查集的。

#include <algorithm>#include <iostream>#include <cstdlib>#include <cstring>#include <cstdio>#include <cmath>using namespace std;typedef struct d_node{int point1;int point2;int weight;}enode;enode edge[25005];//union_setint sets[1001];int rank[1001];void set_inital( int a, int b ){for ( int i = a ; i <= b ; ++ i ) {rank[i] = 0;sets[i] = i;}}int  set_find( int a ){if ( a != sets[a] )sets[a] = set_find( sets[a] );return sets[a];}void set_union( int a, int b ){if ( rank[a] < rank[b] )sets[a] = b;else {if ( rank[a] == rank[b] )rank[a] ++;sets[b] = a;}}//end_union_setint cmp_e( enode a, enode b ){return a.weight < b.weight;}int kruskal( int n, int m ){sort( edge, edge+m, cmp_e );set_inital( 0, n );int sum = 0;for ( int i = 0 ; i < m ; ++ i ) {int A = set_find( edge[i].point1 );int B = set_find( edge[i].point2 );if ( A != B ) set_union( A, B );else {if ( sum ++ ) printf(" ");printf("%d",edge[i].weight);}}return sum;}int main(){int n,m,a,b,c; while ( scanf("%d%d",&n,&m) && n+m ) {for ( int i = 0 ; i < m ; ++ i ) {scanf("%d%d%d",&a,&b,&c);edge[i].point1 = a;edge[i].point2 = b;edge[i].weight = c;}if ( !kruskal( n, m ) )printf("forest");printf("\n");}return 0;}

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