poj 3522 Slim Span

来源：互联网发布：淘宝qq皇冠号专卖店编辑：程序博客网时间：2024/04/28 21:59

求最小生成树的最大边与最小边之差最小利用kruskal

#include <iostream>#include <algorithm>using namespace std;int n,m,parent[20000];struct node{int x,y,w;}tree[20000];int cmp(node aa,node bb){return aa.w<bb.w;}void makeset(){int x;for(x=1;x<=n;x++)parent[x]=x;}int findset(int x){if(x!=parent[x])parent[x]=findset(parent[x]);return parent[x];}void unionset(int x,int y){x=findset(x);y=findset(y);if(parent[x]==parent[y])return ;parent[y]=x;}int kruskal(){int i,j,cnt=0,mini,maxn=9999999999,minc=999999999,flg=0,f;sort(tree,tree+m,cmp);for(j=0;j<m;j++){makeset();cnt=0;for(i=j;i<m;i++){f=0;if(findset(tree[i].x)!=findset(tree[i].y)){cnt++;unionset(tree[i].x,tree[i].y);if(cnt==1)mini=tree[i].w;if(cnt==n-1){flg=1;f=1;maxn=tree[i].w;break;}}}if(f && maxn-mini<minc)minc=maxn-mini;}if(flg==0)return -1;elsereturn minc;}int main(){int i,j,minc=999999999;while(scanf("%d%d",&n,&m)!=EOF){if(!n && !m)break;for(i=0;i<m;i++)scanf("%d%d%d",&tree[i].x,&tree[i].y,&tree[i].w);printf("%d/n",kruskal());}return 0;}