最小生成樹Kruskal算法與並查集及其優化

#include<bits/stdc++.h>

using namespace std;

struct Road{
    int from;
    int to;
    int weight;
    bool operator <(Road b) const{
        return weight<b.weight;
    }
};

int arr[1001];

Road arr2[10001];
/*並查集非遞歸優化*/
int findRoot(int val){
    int tmp=val;
    while(arr[val]>0){
        val=arr[val];
    }
    while(arr[tmp]>0){
        int temp=arr[tmp];
        arr[tmp]=val;
        tmp=temp;
    }
    return val;
}


int main(){
    long long num;
    long long val,temp1,temp2;
    while(scanf("%lld",&num)!=EOF&&num!=0){
        memset(arr,-1,sizeof(arr));
        //for(int i=0;i<1001;i++) cout<<arr[i]<<' ';
        int size=num*(num-1)/2;
        for(int i=0;i<size;i++){
            scanf("%lld%lld%lld",&temp1,&temp2,&val);
            arr2[i].from=temp1;
            arr2[i].to=temp2;
            arr2[i].weight=val;
        }
        sort(arr2,arr2+size);
        //for(int i=0;i<size;i++) cout<<arr2[i].from<<' '<<arr2[i].to<<' '<<arr2[i].weight<<endl;
        int res=0;
        for(int i=0;i<size;i++){
            temp1=findRoot(arr2[i].from);
            temp2=findRoot(arr2[i].to);
            if(temp1!=temp2) {
                arr[temp1]=temp2;   
                res+=arr2[i].weight;
            }
        }
        printf("%d\n",res);

    }

    return 0;
}

1070