王道机试指南第11章---图论---11.3最小生成树
作者:互联网
11.3最小生成树
Kruskal—O(ElogE)
#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
const int MAXN=100;
struct Edge{
int from;
int to;
int length;
// bool operator<(const Edge& e)const{ //??????????????未懂
// return length<e.length;
// }
};
//等价于
bool cmp(Edge a,Edge b){
return a.length<b.length;
}
Edge edge[MAXN*MAXN]; //边是顶点的两倍
int father[MAXN];
int height[MAXN];
void Initial(int n){
for(int i=0;i<=n;i++){
father[i]=i;
height[i]=0;
}
}
int Find(int x){ //查找根节点
if(x!=father[x]){
father[x]=Find(father[x]);
}
return father[x];
}
void Union(int x,int y){
x=Find(x);
y=Find(y);
if(x!=y){
if(height[x]<height[y]){
father[x]=y;
}else if(height[y]<height[x]){
father[y]=x;
}else{
father[y]=x;
height[x]++;
}
}
return;
}
int Kruskal(int n,int edgeNumber){ //返回的是权值之和,传入顶点和边的个数
Initial(n);
sort(edge,edge+edgeNumber,cmp);
int sum=0;
for(int i=0;i<edgeNumber;i++){
Edge current=edge[i];
if(Find(current.from)!=Find(current.to)){
Union(current.from,current.to);
sum+=current.length;
}
}
return sum;
}
int main(){
int n;
while(scanf("%d",&n)!=EOF){
if(n==0){
break;
}
int edgeNumber=n*(n-1)/2;
for(int i=0;i<edgeNumber;i++){
scanf("%d%d%d",&edge[i].from,&edge[i].to,&edge[i].length);
}
int answer=Kruskal(n,edgeNumber);
printf("%d\n",answer);
}
return 0;
}
Prim-O(V²)
Prim+Heap-O(ElogV)
标签:11,current,return,int,father,11.3,---,edge,Find 来源: https://blog.csdn.net/weixin_44411458/article/details/123216336