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++: #include<iostream>
#include<cstdio>
#include<cstring>
#define INF 2100
using namespace std;
int n;
int A[1000][1000];
int d[1000];
bool used[1000];
int D[1000][1000];
 
void Init(int f){
  for(int i=0;i<f;i++){
    for(int j=0;j<f;j++)D[i][j] = INF;
  }
 
}
 
int main(){
  scanf("%d",&n);
  int u,k,C,V;
  Init(n);
  
  for(int i=0;i<n;i++){
      scanf("%d %d",&u,&k);     
      for(int j=0;j<k;j++){
    scanf("%d %d",&V,&C);
    D[u][V] = C;
    D[V][u] = C;
      }     
  }
   
  for(int i=0;i<n;i++)D[i][i] = 0;
  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]);
  }
 
  return 0;
}

C++: #include <climits>
#include <iostream>
#include <utility>
#include <vector>

using namespace std;

void dijkstra(vector<vector<pair<int, int>>>& g, vector<int>& weights) {
    int n_vertex = weights.size();
    vector<bool> visited(n_vertex, false);
    weights[0] = 0;
    while (true) {
        int min_idx;
        int min_weight = INT_MAX;
        for (int i = 0; i < n_vertex; ++i) {
            if (!visited[i] && weights[i] < min_weight) {
                min_idx = i;
                min_weight = weights[i];
            }
        }

        if (min_weight == INT_MAX)
            break;

        visited[min_idx] = true;

        for (int i = 0; i < g[min_idx].size(); ++i) {
            int adj = g[min_idx][i].first;
            int weight_via_idx = weights[min_idx] + g[min_idx][i].second;
            if (!visited[adj] && weight_via_idx < weights[adj]) {
                weights[adj] = weight_via_idx;
            }
        }
    }
}

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

    vector<vector<pair<int, int>>> g(n);
    for (int i = 0; i < n; ++i) {
        int u, k;
        cin >> u >> k;
        for (int j = 0; j < k; ++j) {
            int v, c;
            cin >> v >> c;
            g[i].push_back(make_pair(v, c));
        }
    }

    vector<int> weights(n, INT_MAX);
    dijkstra(g, weights);
    for (int i = 0; i < n; ++i)
        cout << i << ' ' << weights[i] << '\n';
}

C++: #include <bits/stdc++.h>
using namespace std;
#define MAX 100
#define INFTY (1<<21)
#define WHITE 0
#define GRAY 1
#define 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;
}

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

using ll = long long int;
using P = pair<int,int>;
constexpr int INF = 1<<30;

int n;
vector<vector<P> > g;
vector<int> d;

void dijkstra(int s){
    fill(d.begin(), d.end(), INF);
    d[s] = 0;
    priority_queue<P, vector<P>, greater<P> > que;
    que.push(make_pair(d[s],s));

    while(!que.empty()){
        P p = que.top();
        que.pop();
        int v = p.second;
        if(d[v] < p.first) continue;
        int k = int(g[v].size());
        for(int i=0;i<k;i++){
            int u = g[v][i].first, c = g[v][i].second;
            if(d[u] > d[v] + c){
                d[u] = d[v] + c;
                que.push(make_pair(d[u], u));
            }
        }
    }
}

int main(){
    cin >> n;
    g.resize(n);
    d.resize(n);
    for(int i=0;i<n;i++){
        int v, k;
        cin >> v >> k;
        for(int j=0;j<k;j++){
            int u, c;
            cin >> u >> c;
            g[v].push_back(make_pair(u,c));
        }
    }
    dijkstra(0);
    for(int i=0;i<n;i++){
        cout << i << " " << d[i] << endl;
    }
    return 0;
}