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 <stdio.h>
#include <stdint.h>
#include <iostream>
#include <fstream>
#include <cassert>
#include <climits>

#include <vector>
#include <string>
using namespace std;

#define DEBUG (0)

#if DEBUG
#define DPRINTF(...) do { \
    printf("D(L%d) %s: ", __LINE__, __func__); \
    printf(__VA_ARGS__); \
  } while (false)
#else
#define DPRINTF(...)
#endif // DEBUG

/*
   recursive + dfs
*/

const uint8_t kMaxN = 100;
int16_t gWeightOfVij[kMaxN][kMaxN];
int gNumOfVertices;


void printAllWeights()
{
  DPRINTF("Number of vertices %d\n", gNumOfVertices);

  for (int i = 0; i < gNumOfVertices; i++)
  {
    for (int j = 0; j < gNumOfVertices; j++)
    {
      if (j == 0)  DPRINTF("");
      printf(" %d", gWeightOfVij[i][j]);
    }
    cout << endl;
  }
}


void printAllPath()
{
  DPRINTF("Number of vertices %d\n", gNumOfVertices);

  for (int i = 0; i < gNumOfVertices; i++)
  {
    for (int j = 0; j < gNumOfVertices; j++)
    {
      if (gWeightOfVij[i][j] > 0)
        printf("%d -> %d (%d)\n", i, j, gWeightOfVij[i][j]);
    }
  }
}


vector<int16_t> getConnectedVs(int16_t v, const bool visited[])
{
  vector<int16_t> vertices;

  for (int i = 0; i < gNumOfVertices; i++)
  {
    if (gWeightOfVij[v][i] > 0 && !visited[i])
      vertices.push_back(i);
  }

#if 0
  if (vertices.size() > 0)
  {
    for (int i = 0; i < vertices.size(); i++)
    {
      if (i == 0)
        DPRINTF("v from %d to :", v);

      printf(" %d", vertices[i]);
    }

    cout << endl;
  }
#endif

  return vertices;
}


int minSpanningTreeRecursive(int16_t currentV, const bool visited[], string inpPath, string &minPath)
{
  assert(0 <= currentV && currentV < gNumOfVertices);

  bool updatedVisited[gNumOfVertices];

  for (int i = 0; i < gNumOfVertices; i++)
    updatedVisited[i] = visited[i];

  updatedVisited[currentV] = true;

  // This function ensures all of elements are unvisited
  vector<int16_t> nextVs = getConnectedVs(currentV, updatedVisited);

  if (nextVs.size() == 0)
  {
    minPath = to_string(currentV);
    return 0;
  }

  int minV = -1;
  int minScore = INT_MAX;
  string currentPath = to_string(currentV);


  if (inpPath.size())
    currentPath = inpPath + " > " + currentPath;

  for (int i = 0; i < nextVs.size(); i++)
  {
    string searchedPath = "";
    const int16_t nextV = nextVs[i];
    const int score = gWeightOfVij[currentV][nextV] + minSpanningTreeRecursive(nextV, updatedVisited, currentPath, searchedPath);

    if (minScore > score)
    {
      minV = nextV;
      minScore = score;
      minPath = searchedPath;
    }

  }

  {
    if (minPath.size())
      minPath = " > " + minPath;

    minPath = to_string(currentV) + minPath;

    DPRINTF("score %d\n", minScore);
    DPRINTF("  %s | %s\n", currentPath.c_str(), minPath.c_str());
  }

  return minScore;
}


int minSpanningTree()
{
  int16_t startV = 0;
  bool visited[gNumOfVertices];

  for (int i = 0; i < gNumOfVertices; i++)
    visited[i] = false;

  string inpPath = "", minPath;

  return minSpanningTreeRecursive(startV, visited, inpPath, minPath);
}


int main()
{
  cin >> gNumOfVertices; cin.ignore();

  DPRINTF("Number of vertices %d\n", gNumOfVertices);

  for (int i = 0; i < gNumOfVertices; i++)
  {
    for (int j = 0; j < gNumOfVertices; j++)
      cin >> gWeightOfVij[i][j];

    cin.ignore();
  }

#if DEBUG
  DPRINTF("Number of vertices %d\n", gNumOfVertices);
  //printAllWeights();
  printAllPath();
#endif // DEBUG

  cout << minSpanningTree() << endl;

  return 0;
}

C++: #define _USE_MATH_DEFINES
#include<iostream>
#include<algorithm>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<deque>
#include<queue>
#include<map>
#include<set>
#define ll long long
#define str string
#define ld long double
#define vec vector
#define vll vec<ll>
#define rep(i,a,b) for(ll i=a;i<b;i++)
#define rrep(i,b,a) for(ll i=b;i>=a;i--)
#define ALL(a) a.begin(),a.end()
#define rALL(a) a.rbegin(),a.rend()
#define kai "\n"
#define yuque priority_queue
#define ryuque(t) priority_queue<t,vec<t>,greater<t>>
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define mie min_element
#define mae max_element
#define tos to_string
#define sep setprecision
#define MOD 1000000007ll
using namespace std;
void solve();
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout << fixed;
	solve();
}

//nCk(mod p)
const ll NUM = 2;
ll fac[NUM], finv[NUM], inv[NUM];
void cmodf(ll p = MOD) {
	fac[0] = fac[1] = 1;
	finv[0] = finv[1] = 1;
	inv[1] = 1;
	rep(i, 2, NUM) {
		fac[i] = fac[i - 1] * i%p;
		inv[i] = p - inv[p%i] * (p / i) % p;
		finv[i] = finv[i - 1] * inv[i] % p;
	}
}
ll cmod(ll n, ll k, ll p = MOD) {
	return fac[n] * (finv[k] * finv[n - k] % p) % p;
}

//最大公約数
ll gcd(ll n, ll m) {
	ll k = n % m;
	while (k != 0) { n = m; m = k; k = n % m; }
	return m;
}
ll gcd(vector<ll> a) {
	rep(i, 1, a.size()) {
		ll k = a[i - 1] % a[i];
		while (k != 0) {
			a[i - 1] = a[i];
			a[i] = k;
			k = a[i - 1] % a[i];
		}
	}
	return a.back();
}

//最小公倍数
ll lcm(ll n, ll m) {
	ll t = n * m, k = n % m;
	while (k != 0) { n = m; m = k; k = n % m; }
	return t / m;
}
ll lcm(vector<ll> a) {
	ll n;
	rep(i, 1, a.size()) {
		n = a[i - 1] * a[i];
		ll k = a[i - 1] % a[i];
		while (k != 0) {
			a[i - 1] = a[i];
			a[i] = k;
			k = a[i - 1] % a[i];
		}
		n /= a[i];
		a[i] = n;
	}
	return n;
}

//keyの小さい方から探していった時に初めてvalueがjoken以上になる時のkey（keyが増えたらvalueも増えるか同じになるとき）
ll value(ll key) {
	/*変更*/
	return 0;
}
ll mink(ll lkey, ll rkey/*ここも調べる*/, ll joken) {
	ll mkey;
	while (lkey != rkey) {
		mkey = (lkey + rkey) / 2;
		if (value(mkey) >= joken)rkey = mkey;
		else lkey = mkey + 1;
	}
	return rkey;
}

//ペア配列の整理
struct pea {
	ll f, s;
	bool operator<(const pea &c)const {
		return f != c.f ? f < c.f : s < c.s;
	};
};

//変数定義

//再帰関数

//アルゴリズム
void solve() {
	ll n; cin >> n;
	vec<vll> c(n, vll(n));
	rep(i, 0, n)rep(j, 0, n)cin >> c[i][j];
	ll ans = MOD;
	rep(i, 0, 1) {
		vec<vll> a(n, vll(n));
		rep(j, 0, n)rep(k, 0, n)a[j][k] = c[j][k];
		ll t = 0;
		vll b; b.pub(i);
		rep(j, 0, n)a[j][i] = -1;
		while (b.size() != n) {
			ll m = MOD, kk;
			rep(j, 0, b.size()) {
				rep(k, 0, n) {
					if (a[b[j]][k] != -1 && a[b[j]][k] < m) {
						kk = k;
						m = a[b[j]][kk];
					}
				}
			}
			t += m;
			b.pub(kk);
			rep(j, 0, n)a[j][kk] = -1;
		}
		ans = min(ans, t);
	}
	cout << ans << kai;
}