Go: package main

import (
	"bufio"
	"container/heap"
	"fmt"
	"os"
	"strconv"
)

type Node struct {
	id     int
	weight int
}

func init() {
	sc.Split(bufio.ScanWords)
}

type NodeHeap []Node

func (h NodeHeap) Len() int           { return len(h) }
func (h NodeHeap) Less(i, j int) bool { return h[i].weight < h[j].weight }
func (h NodeHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }

func (h *NodeHeap) Push(x interface{}) {
	*h = append(*h, x.(Node))
}

func (h *NodeHeap) Pop() interface{} {
	old := *h
	n := len(old)
	x := old[n-1]
	*h = old[0 : n-1]
	return x
}

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

func scanString() string {
	sc.Scan()
	return sc.Text()
}

func init() {
	sc.Split(bufio.ScanWords)
}

func main() {
	n := scanInt()

	list := make([][]int, n)
	seen := make([]bool, n)
	for i := range list {
		list[i] = make([]int, n)
		for j := range list[i] {
			list[i][j] = scanInt()
		}
	}

	start := Node{id: 0, weight: 0}
	h := &NodeHeap{start}
	heap.Init(h)

	sum := 0
	for h.Len() > 0 {
		node := heap.Pop(h).(Node)
		if seen[node.id] {
			continue
		}
		seen[node.id] = true
		sum += node.weight

		for i, w := range list[node.id] {
			if w < 0 {
				continue
			}
			heap.Push(h, Node{id: i, weight: w})
		}
	}

	fmt.Println(sum)
}

C++: #include<bits/stdc++.h>
using namespace std;

#define rep(i,n) for(int i = 0; i < n; i++)
#define Rep(i,n) for(int i = 1; i <= n; i++)
#define sz(x) int(x.size())
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define YesorNo(a) printf(a ? "Yes\n" : "No\n")
#define endl '\n'
#define fi first
#define se second
using ll = long long;
using P = pair<int,int>;
using Pl = pair<ll,ll>;
template<class T> using V = vector<T>;
const int dx[] = {0,1,0,-1,1,1,-1,-1};
const int dy[] = {1,0,-1,0,1,-1,-1,1};
const int inf = (1<<30)-1;
const ll infll = (1LL<<62)-1;
ll ceil(const ll &a, const ll &b){return ((a)+(b)-1)/b;}
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }

ll MinimumSpanningTree(const V<V<pair<ll, int>>> &g, int n) { // 最小全域木
    using pi = pair<ll,int>; // pair = (cost, to);
    ll res = 0;

    vector<int> v;
    v.push_back(0);
    priority_queue<pi, vector<pi>, greater<pi>> pq; 
    vector<bool> seen(n);
    seen[0] = true;
    for(pi nv : g[0]) {
        pq.push(nv);
    }

    while(sz(v) != n) {
        pi p = pq.top(); pq.pop();
        if(seen[p.se]) continue;
        v.push_back(p.se);
        seen[p.se] = true;
        res += p.fi;
        for(pi nv : g[p.se]) {
            if(!seen[nv.se])
                pq.push(nv);
        }
    }
    return res;
}

int main(){
    int n;
    cin >> n;
    V<V<pair<ll,int>>> g(n);
    rep(i,n)rep(j,n) {
        ll a;
        cin >> a;
        if(a == -1) continue;
        g[i].emplace_back(a,j);
    }
    ll ans = MinimumSpanningTree(g,n);
    cout << ans << endl;
}

C++: #include <cstdio>
#include <climits>
#include <vector>

int w[100][100];
std::vector<int> mst;
std::vector<int> others;
typedef std::vector<int>::iterator itr;

int minimum(){
    if(others.size()<=0)return 0;
    int candiW=INT_MAX;
    itr candiI;
    for(itr i=mst.begin();i!=mst.end();i++){
        for(itr j=others.begin();j!=others.end();j++){
            if(w[*i][*j]<candiW){
                candiW = w[*i][*j];
                candiI = j;
            }
        }
    }
    mst.push_back(*candiI);
    printf("%d ",*candiI);
    others.erase(candiI);
    return candiW + minimum();
}

int main(){
    int i, j, n;
    scanf("%d",&n);
    for(i=0;i<n;i++){
        for(j=0;j<n;j++){
            scanf("%d",&w[i][j]);
            if(w[i][j]==-1)w[i][j]=INT_MAX;
        }
    }
    mst.push_back(0);
    for(i=1;i<n;i++)others.push_back(i);
    printf("%d\n",minimum());
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
#define P(x) cout << (x) << '\n'
#define p(x) cout << (x)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define vv(type, c, m, n, i) vector<vector<type>> c(m, vector<type>(n, i));
#define rep(i,a,n) for(int i=(a), i##_len=(n); i<i##_len; ++i)
#define rrep(i,a,n) for(int i=(a), i##_len=(n); i>i##_len; --i)
#define len(x) ((int)(x).size())
#define mp make_pair
#define eb emplace_back
typedef long long ll;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<long long> vll;
typedef vector<string> vs;
typedef vector<bool> vb;
constexpr int MAX = 101;
constexpr int INF = 1<<21;
enum Color { WHITE = 0, GRAY, BLACK };
int n;
vv(int, M, MAX, MAX, INF);
inline int prim() {
	vi color(n, WHITE);
	int d[n];
	d[0] = 0;
	rep(i, 1, n) d[i] = INF;
    int minv, u;
    while(true) {
        minv = INF;
        u = -1;
        rep(i, 0, n) {
            if(minv > d[i] && color[i] != BLACK) {
                u = i;
                minv = d[i];
            }
        }
        if(u == -1) break;
        color[u] = BLACK;
        rep(v, 0, n) {
            if(color[v] != BLACK && d[v] > M[u][v]) {
                d[v] = M[u][v];
                color[v] = GRAY;
            }
        }
    }
    return accumulate(all(d), 0);
}
int main() {
    cin >> n;
    int e;
    rep(i, 0, n) {
        rep(j, 0, n) {
            cin >> e;
            if(e != -1) M[i][j] = e;
        }
    }
    P(prim());
    return 0;
}

C++: #include <iostream>

using namespace std;

int n;
int adja[100][100];

int spanning() {
    int visit[100] = {}, cost = 0;
    visit[0] = 1;
    while (1) {
        int minj, minc = 2001;
        for (int i = 0; i < n; ++i) {
            if (visit[i]) {
                for (int j = 0; j < n; ++j) {
                    if (adja[i][j] >= 0 && !visit[j] && minc > adja[i][j]) {
                        minc = adja[i][j];
                        minj = j;
                    }
                }
            }
        }
        if (minc == 2001)
            break;
        cost += minc;
        visit[minj] = 1;
    }
    return cost;
}

int main() {
    cin >> n;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            cin >> adja[i][j];
        }
    }
    cout << spanning() << endl;

    return 0;
}

C++: #include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;

int x[10000][10000];
int MIN[10000];
int MINX = 0;
int MINZ = 10000000;

int main() {
	memset(MIN, 127, sizeof(MIN));
	int n, a;
	cin >> n;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			cin >> a;
			x[i][j] = a;
		}
	}
	for(int i=0;i<n;i++){
	    for(int j=0;j<n;j++){
	        if(x[i][j]!=-1){
	            MIN[i]=min(x[i][j],MIN[i]);
	        }
	    }
	}
	for(int i=0;i<n;i++){
	    MINX=0;
	    for(int j=0;j<n;j++){
	        MINX += min[j];
	    }
	    MINZ=min(MINZ,MINX);
	}
	cout<<MINZ<<endl;
	return 0;
}

C++: #include<stdio.h>

static const int MAX = 500;
static const int INFTY = (1<<21);

main(){
  int n, i, j, e, sum,M[MAX][MAX]={0};
  int u,minV,INT_MAX,A[MAX]={INFTY},key[MAX]={INFTY};
  /*

    your code


   */

  scanf("%d", &n);
  
  for ( i = 0; i< n; i++ ){
    for ( j = 0; j < n; j++ ){
      scanf("%d", &e);
      M[i][j] = (e==-1)?INFTY:e;
    }
  }
  
  
  while(1){
    minV = 
      for(i=1;i<=n;i++){
        if((i < minV) && 

  






















  sum = 0;

  for ( i = 0; i < n; i++ ){
    if ( p[i] != -1 ) sum += M[i][p[i]];
  }

  printf("%d\n", sum);

  retur
}