Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

const (
	white int = iota
	gray
	black
)

type node struct {
	id     int
	parent int
	edge   []int
	weight []int
	color  int
}

type graph struct {
	nodes    []node
	distance []int
}

var infty = 1 << 32
var null = -1

func constructgraph() *graph {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	n := nextInt(sc)

	g := &graph{make([]node, n), make([]int, n)}

	for i := 0; i < n; i++ {
		id := nextInt(sc)
		edges := nextInt(sc)
		n := node{}
		n.id = id
		n.edge = make([]int, edges)
		n.weight = make([]int, edges)
		n.color = white
		for j := 0; j < edges; j++ {
			to := nextInt(sc)
			w := nextInt(sc)
			n.edge[j] = to
			n.weight[j] = w
		}
		g.nodes[id] = n
	}
	return g
}

func nextInt(sc *bufio.Scanner) int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

func (g *graph) preparedijkstra(s int) {
	for i := 0; i < len(g.nodes); i++ {
		g.nodes[i].color = white
		g.nodes[i].parent = null
		g.distance[i] = infty
	}
	g.distance[s] = 0
}

func (g *graph) dijkstra(s int) []int {
	g.preparedijkstra(s)

	for {
		var u int
		mincost := infty
		for i, d := range g.distance {
			if g.nodes[i].color != black && mincost > d {
				mincost = d
				u = i
			}
		}

		if mincost == infty {
			break
		}

		g.nodes[u].color = black

		for i, e := range g.nodes[u].edge {
			if g.nodes[e].color != black {
				if g.distance[e] > g.distance[u]+g.nodes[u].weight[i] {
					g.distance[e] = g.distance[u] + g.nodes[u].weight[i]
					g.nodes[e].parent = u
					g.nodes[e].color = gray
				}
			}
		}
	}
	return g.distance
}

func printShortestPath(d []int) {
	for i, v := range d {
		fmt.Printf("%d %d\n", i, v)
	}
}

func main() {
	g := constructgraph()
	d := g.dijkstra(0)
	printShortestPath(d)
}

C++: #include<iostream>
using namespace std;
static const int MAX =100;
static const int INFTY = (1<<21);
static const int WHITE = 0;
static const int GRAY =1;
static const int BLACK=2;

int n, M[MAX][MAX];

int prim(){
  int u,minv;
  int d[MAX],p[MAX],color[MAX];

  for(int i = 0;i<n;i++){
    d[i]=INFTY;
    p[i]=-1;
    color[i]=WHITE;
  }
  d[0]=0;

  while(1){
    minv=INFTY;
    u=-1;
    for(int i=0;i<n;i++){
      if(minv>d[i]&&color[i]!=BLACK){
      u=i;
      minv=d[i];
    }
  }
  if(u==-1)break;
  color[u]=BLACK;
  for(int v =0;v<n;v++){
    if(color[v]!=BLACK&& M[u][v]!=INFTY){
      if(d[v]>M[u][v]){
      d[v]=M[u][v];
      p[v]=u;
      color[v]=GRAY;
      }
    }
  }
  }
  int sum=0;
  for(int i=0;i<n;i++){
    if(p[i]!=-1) sum+=M[i][p[i]];
  }
  return sum;
}

int main(){
  cin >>n;

  for(int i=0;i<n;i++){
    for(int j=0;j<n;j++){
      int e; cin >>e;
      M[i][j] =(e==-1) ? INFTY : e;
    }
  }

  cout << prim() << endl;

  return 0;
}

C++: #include<cstdio>
#include<vector>
#include<algorithm>
#include<utility>
#include<numeric>
#include<iostream>
#include<array>
#include<string>
#include<sstream>
#include<stack>
#include<queue>
#include<list>
#include<functional>
#define _USE_MATH_DEFINES

#include<math.h>
#include<map>

#define SENTINEL 1000000001

#define min(a,b) (a)>(b)?(b):(a)
#define max(a,b) (a)>(b)?(a):(b)

using namespace std;

/*struct OwnNode
{
	vector<int> to;
	vector<int> to_cost;

	int id;
	bool checked;
	int cost;

	OwnNode(int id):id(id),checked(false),cost(-1){}

	bool operator<(const OwnNode& node)const
	{
		return cost < node.cost;
	}

	bool operator>(const OwnNode& node)const
	{
		return cost > node.cost;
	}

	OwnNode operator-(const OwnNode& node)const
	{
		return cost - node.cost;
	}
};*/

int d[100][100];

int main()
{
	int n;
	cin >> n;

	for (int i = 0; i < n; i++)for (int j = 0; j < n; j++)
	{
		d[i][j] = 100000000;
	}

	for (int i = 0; i < n; i++)
	{
		d[i][i] = 0;
	}

	for (int i = 0; i < n; i++)
	{
		int id, k;
		cin >> id >> k;
		for (int j = 0; j < k; j++)
		{
			int v, c;
			cin >> v >> c;
			d[id][v] = c;
		}
	}

	for (int k = 0; k < n; k++)
	{
		for (int i = 0; i < n; i++)
		{
			for (int j = 0; j < n; j++)
			{
				d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
			}
		}
	}

	for (int i = 0; i < n; i++)
	{
		printf("%d %d\n", i, d[0][i]);
	}

	/*vector<OwnNode> nodes;

	for (int i = 0; i < n; i++)
	{
		int id, k;
		cin >> id >> k;

		nodes.push_back(OwnNode(id));

		for (int j = 0; j < k; j++)
		{
			int v, c;
			cin >> v >> c;
			nodes[i].to.push_back(v);
			nodes[i].to_cost.push_back(c);
		}
	}

	priority_queue<OwnNode, vector<OwnNode>, greater<OwnNode>> pq;

	nodes[0].cost = 0;
	pq.push(nodes[0]);

	while (pq.size() != 0)
	{
		OwnNode tn = pq.top();
		pq.pop();

		nodes[tn.id].checked = true;

		for (int i = 0; i != tn.to.size(); i++)
		{
			if (nodes[tn.to[i]].checked)continue;
			if (nodes[tn.to[i]].cost == -1)
			{
				nodes[tn.to[i]].cost = tn.to_cost[i];
			}
			else
			{
				nodes[tn.to[i]].cost = min(nodes[tn.to[i]].cost, tn.to_cost[i] + tn.cost);
			}
			pq.push(nodes[tn.to[i]]);
		}
	}

	for (auto& node : nodes)
	{
		
		printf("%d %d\n", node.id, node.cost);
	}*/

	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#define MAX 101
#define INF 1000001
using namespace std;

int n, isSelected[MAX], dist[MAX];
vector<pair<int, int>> ver[MAX];

void initDijkstra(void);
void dijkstra(void);
bool doesFinished(void);

int main() {
	int i, j, id, k, v, c;
	cin >> n;
	for (i = 0; i < n; i++) {
		cin >> id >> k;
		for (j = 0; j < k; j++) {
			cin >> v >> c;
			ver[id].push_back(make_pair(v, c));
		}
	}

	initDijkstra();

	while (!doesFinished())dijkstra();

	for (i = 0; i < n; i++) {
		cout << i << " " << dist[i] << endl;
	}

	return 0;
}

void initDijkstra(void) {

	dist[0] = 0;
	isSelected[0] = 1;
	for (int i = 1; i <= n; i++)dist[i] = INF;

	vector<pair<int, int>>::iterator itv;

	for (itv = ver[0].begin(); itv != ver[0].end(); itv++) {
		dist[itv->first] = itv->second;
	}

}

void dijkstra(void) {
	int i, minu, mindist = INF;
	vector<pair<int, int>>::iterator itv;

	for (i = 0; i < n; i++) {
		if (isSelected[i] == 0)continue;
		for (itv = ver[i].begin(); itv != ver[i].end(); itv++){
			if (isSelected[itv->first] == 1)continue;
			if (itv->second < mindist) {
				mindist = itv->second;
				minu = itv->first;
			}
		}
	}
	isSelected[minu] = 1;
	//dist[minu] = dist[minp] + mindist;
	for (itv = ver[minu].begin(); itv != ver[minu].end(); itv++) {
		if (isSelected[itv->first] == 1)continue;
		dist[itv->first] = min(dist[minu] + itv->second, dist[itv->first]);
	}
}

bool doesFinished(void) {
	for (int i = 0; i < n; i++) {
		if (isSelected[i] == 0)return false;
	}
	return true;
}