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<cstdio>
#include<queue>
#include<utility>
#include<string.h>
#include<vector>
using namespace std;
const int INF = 0x3f3f3f3f;
const int MAXN = 250;
const int MAXM = 1000;
int n, m;
int vis[MAXN];
struct Edge{
	int to, weight, next;
}edge[MAXM];
int head[MAXN];
int cnt;
int d[MAXN];
void addEdge(int from, int to, int weight){
	edge[cnt].to = to;
	edge[cnt].weight = weight;
	edge[cnt].next = head[from];
	head[from] = cnt++;
}
void SPFA(int start){
	queue<int> q;
	memset(d, INF, sizeof(d));
	memset(vis, 0, sizeof(vis));
	q.push(start);
	d[start] = 0;
	while (!q.empty()){
		int from = q.front(); q.pop();
		vis[from] = 0;
		for (int i = head[from]; i != -1; i = edge[i].next){
			int to = edge[i].to;
			int weight = edge[i].weight;
			if (d[to] > d[from] + weight){
				d[to] = d[from] + weight;
				if (!vis[to]){
					vis[to] = 1;
					q.push(to);
				}
			}
		}
	}
}
int main(){
	int from, to, weight, k;
	while (scanf("%d", &n) != EOF){
		m = 0;
		memset(head, -1, sizeof(head));
		for (int i = 0; i < n; i++){
			scanf("%d%d", &from, &k);
			m += k;
			for (int i = 0; i < k; i++){
				scanf("%d%d", &to, &weight);
				addEdge(from, to, weight);
			}
		}
		SPFA(0);
		for (int i = 0; i < n; i++) printf("%d %d\n", i, d[i]);
	}
	return 0;
}

C++: #include <iostream>
// #include <vector>
using namespace std;

const int MAX = 100;
const int INFTY = (1 << 21);
int n;
int M[MAX][MAX];

void dijkstra(int s){
  int color[MAX], d[MAX], p[MAX];
  // vector<int> S;
  for(int i=0;i<n;i++){
    color[i] = 0;
    d[i] = INFTY;
    p[i] = -1;
  }
  d[s] = 0;
  p[s] = -1;
  color[0] = 1;

  while(true){
    int mincost = INFTY;
    int u = -1;
    for(int i=0;i<n;i++){
      if(color[i] != 2 && d[i] < mincost){
        mincost = d[i];
        u = i;
      }
    }

    // if(mincost == INFTY) break;
    if(u == -1) break;
    color[u] = 2;

    // S.push_back(u);
    for(int i=0;i<n;i++){
      if(M[u][i] != -1 && (d[i] > M[u][i] + d[u])){
        d[i] = M[u][i] + d[u];
        color[i] = 1;
        p[i] = u;
      }
    }
  }

  for(int i=0;i<n;i++){
    cout << i << " " << 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;

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

  dijkstra(0);
  return 0;
}

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

int n;
vector<pair<int, int>> *adj;
int *d;

void dijkstra() {
    priority_queue<pair<int, int>> PQ;
    int d[n], color[n];

    for (int i = 0; i < n; i++) {
        d[i] = INFTY;
        color[i] = WHITE;
    }
    d[0] = 0;
    PQ.push(make_pair(0, 0));

    while (!PQ.empty()) {
        pair<int, int> f = PQ.top();
        PQ.pop();

        int u = f.second;
        color[u] = BLACK;

        if (d[u] < f.first * (-1)) { continue; }

        for (int j = 0; j < adj[u].size(); j++) {
            int v = adj[u][j].first;
            if (color[v] == BLACK) { continue; }
            if (d[u] + adj[u][j].second < d[v]) {
                d[v] = d[u] + adj[u][j].second;
                PQ.push(make_pair(d[v] * (-1), v));
                color[v] = GRAY;
            }
        }
    }
    
    for (int i = 0; i < n; i++) {
        printf("%d %d\n", i, d[i]);
    }
}

int main() {
    scanf("%d", &n);
    adj = new vector<pair<int, int>>[n];
    for (int i = 0; i < n; i++) {
        int u, k;
        scanf("%d %d", &u, &k);
        for (int j = 0; j < k; j++) {
            int v, c;
            scanf("%d %d", &v, &c);
            adj[u].push_back(make_pair(v, c));
        }
    }

    dijkstra();

    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
#define INF 9999999
using namespace std;

const int maxn = 10000 + 5;
const int maxm = 500000 + 5;

struct Edge{
	int next;
	int to;
	int value;
	Edge():next(0),to(0),value(INF){}
}G[maxm];

struct Node{
	int to;
	int dist;
	bool operator < (const Node& rhs) const{
		return dist > rhs.dist;
	}
};

int head[maxn],cnt;
int dis[maxn];
bool vis[maxn];

int n;

void Insert(int u,int v,int c){
	G[++cnt].next = head[u];
	G[cnt].to = v;
	G[cnt].value = c;
	head[u] = cnt;
}

void init(){
	memset(dis,INF,sizeof(dis));
	memset(vis,false,sizeof(vis));
}

priority_queue<Node >Q;

void Dijkstar(int s){
	dis[s] = 0;
	Q.push((Node){s,0});
	while(!Q.empty()){
		int u = Q.top().to;Q.pop();
		if(vis[u])continue;
		vis[u] = true;
		for(int e = head[u];e; e = G[e].next){
			int v = G[e].to;
			if(dis[u] + G[e].value < dis[v] && !vis[v]){
				dis[v] = dis[u] + G[e].value;
				Q.push((Node){v,dis[v]});
			}
		}
	}
}

int main(){
	init();
	scanf("%d",&n);
	for(int i = 0;i < n; i++){
		int u,m;
		scanf("%d%d",&u,&m);
		for(int j = 0;j < m; j++){
			int v,c;
			scanf("%d%d",&v,&c);
			Insert(u,v,c);
		}
	}
	Dijkstar(0);
	for(int i = 0;i < n; i++){
		printf("%d %d\n",i,dis[i]);
	}
}