#include <iostream>
#include <algorithm>
using namespace std;
template<typename T=int>
inline T read(){
    T X=0; bool flag=1; char ch=getchar();
    while(ch<'0' || ch>'9'){if(ch=='-') flag=0; ch=getchar();}
    while(ch>='0' && ch<='9') X=(X<<1)+(X<<3)+ch-'0',ch=getchar();
    if(flag) return X;
    return ~(X-1);
}

template<typename T=int>
inline void write(T X){
    if(X<0) putchar('-'),X=~(X-1);
    T s[20],top=0;
    while(X) s[++top]=X%10,X/=10;
    if(!top) s[++top]=0;
    while(top) putchar(s[top--]+'0');
    putchar('\n');
}

const int N=105;
struct edge{
    int u,v,w;
    bool operator<(edge a){
        return this->w<a.w;
    }
}e[N*N];
int n,x,top;

template<class T=int>
class set{
    public:
        set(){
            f=new T[N];
            for(int i=0; i<N; i++){
                f[i]=0;
            }
        }
        ~set(){
            delete[] f;
        }
        T find(T x){
            if(f[x]==x) return x;
            else return f[x]=find(f[x]);
        }
        void merge(T x,T y){
            f[find(x)]=find(y);
        }
    private:
        T *f;
};

template<typename T=int>
T kruskal(int n,int m){
    sort(e+1,e+m+1);
    set s;
    T ans=0;
    int cnt=1;
    for(int i=1; i<=m; i++){
        if(s.find(e[i].u)!=s.find(e[i].v)){
            ans+=e[i].w;
            s.merge(e[i].u,e[i].v);
            if(++cnt==n){
                break;
            }
        }
    }
    return ans;
}

int main(){
    n=read();
    for(int i=1; i<=n; i++){
        for(int j=1; j<=n; j++){
            x=read();
            if(j>i){
                e[++top]=edge{i,j,x};
            }
        }
    }
    write(kruskal(n,top));
    return 0;
}

样例输出 $0$ /kel，和第一篇题解 "差不多" 啊。。