Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

var infty = 1000000000

type DirectedGraphNodeID int

type DirectedGraphNode struct {
	key         DirectedGraphNodeID
	adjacents   []*DirectedGraphNode
	costs       []int
	distance    int
	predecessor *DirectedGraphNode
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]*DirectedGraphNode, nNodes)
	for i := 0; i < nNodes; i++ {
		node := DirectedGraphNode{}
		node.key = DirectedGraphNodeID(i)
		node.distance = infty
		graph.nodes[i] = &node
	}
	return &graph
}

type DirectedGraph struct {
	nodes []*DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(i, j DirectedGraphNodeID, cost int) {
	g.nodes[i].adjacents = append(g.nodes[i].adjacents, g.nodes[j])
	g.nodes[i].costs = append(g.nodes[i].costs, cost)
}

func (g *DirectedGraph) print() {
	for i := 0; i < len(g.nodes); i++ {
		node := g.nodes[i]
		key := node.key
		strings := []string{strconv.Itoa(int(key)), strconv.Itoa(node.distance)}
		for j := 0; j < len(node.adjacents); j++ {
			nodeJ := fmt.Sprintf("(%v, %v)", node.adjacents[j].key, node.costs[j])
			strings = append(strings, nodeJ)
		}
		fmt.Printf("%v\n", strings)
	}
}

func (g *DirectedGraph) relaxEdge(l, r *DirectedGraphNode, w int) {
	if r.distance > l.distance+w {
		// fmt.Printf("%v -> %v, %v\n", l.key, r.key, l.distance+w)
		r.distance = l.distance + w
		r.predecessor = l
	}
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	graph := newDirectedGraph(nNodes)

	for i := 0; i < nNodes; i++ {
		iNode := DirectedGraphNodeID(nextInt())
		nAdjacent := nextInt()
		for j := 0; j < nAdjacent; j++ {
			jNode := DirectedGraphNodeID(nextInt())
			cost := nextInt()
			graph.setAdjacency(iNode, jNode, cost)
		}
	}

	graph.nodes[0].distance = 0
	for iNode := 0; iNode < nNodes; iNode++ {
		for iLeft := 0; iLeft < len(graph.nodes); iLeft++ {
			nodeLeft := graph.nodes[iLeft]
			for iRight := 0; iRight < len(nodeLeft.adjacents); iRight++ {
				nodeRight := nodeLeft.adjacents[iRight]
				cost := nodeLeft.costs[iRight]
				graph.relaxEdge(nodeLeft, nodeRight, cost)
			}
		}
	}

	// graph.print()

	for iNode := 0; iNode < len(graph.nodes); iNode++ {
		node := graph.nodes[iNode]
		fmt.Println(node.key, node.distance)
	}
}

C++: import java.util.ArrayList;
import java.util.Arrays;
import java.util.PriorityQueue;
import java.util.Scanner;

public class Main {
    int[] distTo = null;
    int[] parentOf = null;

    public Dijkstra(ArrayList<ArrayList<Edge>> G){
        distTo = new int[G.size()];
        Arrays.fill(distTo, Integer.MAX_VALUE);
        parentOf = new int[G.size()];

        PriorityQueue<SDto> pq = new PriorityQueue<>();

        pq.add(new SDto(0, 0, -1));
        while (!pq.isEmpty()) {

            SDto optim = pq.poll();

            if (optim.d < distTo[optim.v]) {
                distTo[optim.v] = optim.d;
                parentOf[optim.v] = optim.from;
                for (Edge e : G.get(optim.v)) {
                    if (optim.from != e.v) { // prevent go back
                        pq.add(new SDto(e.v, distTo[optim.v] + e.c, optim.v));
                    }
                }

            }
        }

    }

    private static class SDto implements Comparable<SDto> { // Shortest distance to vertex
        int v, d, from;

        SDto(int v, int d, int from) {
            this.v = v;
            this.d = d;
            this.from = from;
        }

        @Override
        public int compareTo(SDto that) {
            if(this.d > that.d) return 1;
            else if(this.d < that.d) return -1;
            return 0;
        }


    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        int n = in.nextInt();

        ArrayList<ArrayList<Edge>> G = new ArrayList<>(n);
        for (int i = 0; i < n; i++) {
            G.add(new ArrayList<>());
        }

        for (int i = 0; i < n; i++) {
            int u = in.nextInt();
            int k = in.nextInt();
            for (int j = 0; j < k; j++) {
                int v = in.nextInt(), c = in.nextInt();
                G.get(i).add(new Edge(v, c));
                G.get(v).add(new Edge(i, c));
            }
        }

        Main dijkstra = new Main(G);

        for (int i = 0; i < G.size(); i++) {
            System.out.printf("%d %d\n", i, dijkstra.distTo[i]);
        }
    }
}

class Edge {
    int v, c;

    Edge(int v, int c) {
        this.v = v;
        this.c = c;
    }

    @Override
    public String toString() {
        return String.format("(v=%d, c=%d)", v, c);
    }
}

C++: #include <iostream>
#include <vector>
#include <stack>
#include <queue>

using namespace std;

static const long long FAR = (1LL << 21);
static const int N = 100;

int n, m[N][N];
bool visited[N];
int d[N], p[N];

void dijskra(){
	for (int i = 0; i < n; ++i) {
		d[i] = FAR;
		visited[i] = false;
	}

	d[0] = 0;
	while (true) {
		int mi = FAR;
		int u = -1;
		for (int i = 0; i < n; ++i) {
			if (!visited[i] && d[i] < mi){
				u = i;
				mi = d[i];
			}
		}

		if (-1 == u) break;
		visited[u] = true;

		for (int v = 0; v < n; ++v) {
			if (!visited[v] && (m[u][v] != FAR) && (d[u] + m[u][v] < d[v])) {
				d[v] = d[u] + m[u][v];
			}
		}
	}

	for (int i = 0; i < n; ++i)
		cout << i << " " << ((d[i] == FAR) ? -1 : d[i]) << endl;
}

int main()
{
	cin >> n;
	for (int i = 0; i < n; ++i){
		for (int j = 0; j < n; ++j) m[i][j] = FAR;
	}

	for (int i = 0; i < n; ++i) {
		int u, k; cin >> u >> k;
		for (int j = 0; j < k; ++j)	{
			int v, e; cin >> v >> e;
			m[u][v] = e;
		}
	}
	dijskra();

	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>

using namespace std;

#define MAX_N 100
#define INF 100000 * 100 + 1

int cost[MAX_N][MAX_N];
int d[MAX_N];
bool used[MAX_N];
int V;

void dijkstra(int s) {
	fill_n(d, V, INF);
	fill_n(used, V, false);
	d[s] = 0;

	while (1) {
		int v = -1;
		for (int u = 0; u < V; u++)
			if (!used[u] && (v == -1 || d[u] < d[v]))
				v = u;

		if (v == -1)
			break;

		used[v] = true;

		for (int u = 0; u < V; u++)
			d[u] = min(d[u], d[v] + cost[v][u]);
	}
}

int main() {
	int n;
	cin >> n;
	V = n;
	for (int i = 0; i < n; i++) {
		int u, k;
		cin >> u >> k;
		fill_n(cost[u], n, INF);
		for (int j = 0; j < k; j++) {
			int v, c;
			cin >> v >> c;
			cost[u][v] = c;
		}
	}
	dijkstra(0);
	for (int i = 0; i < n; i++) {
		cout << i << " " << d[i] << endl;
	}
	
	return 0;
}

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];

void dijkstra()
{
  int minv;
  int d[MAX],color[MAX];

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

  d[0]=0;
  color[0]=GRAY;
  while(1)
    {
      minv=INFTY;
      int 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]>d[u]+M[u][v])
		{
		  d[v]=d[u]+M[u][v];
		  color[v]=GRAY;
		}
	    }
	}
    }
  for(int i=0;i<n;i++)
    {
      cout<<i<<" "<<(d[i]==INFTY?-1:d[i])<<endl;
    }
}

int main()
{
  cin>>n;
  for(int i=0;i<n;i++)
    {
      for(int j=0;j<n;j++)
	M[i][j]=INFTY;
    }

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

  dijkstra();

  return 0;
}