Go: package main

import (
	"bufio"
	"container/heap"
	"fmt"
	"os"
	"strconv"
)

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
const INF = 1 << 60

type Edge struct {
	to, cost int
}

type Node struct {
	id, cost int
}

type PQ []Node

func (pq PQ) Len() int           { return len(pq) }
func (pq PQ) Less(i, j int) bool { return pq[i].cost < pq[j].cost }
func (pq PQ) Swap(i, j int)      { pq[i], pq[j] = pq[j], pq[i] }

func (pq *PQ) Push(x interface{}) {
	*pq = append(*pq, x.(Node))
}

func (pq *PQ) Pop() interface{} {
	old := *pq
	n := len(old)
	x := old[n-1]
	*pq = old[0 : n-1]
	return x
}

func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	E := make([][]Edge, N)
	for i := 0; i < N; i++ {
		id, k := sc.nextInt(), sc.nextInt()
		E[id] = make([]Edge, k)
		for j := 0; j < k; j++ {
			to, cost := sc.nextInt(), sc.nextInt()
			E[id][j] = Edge{to, cost}
		}
	}

	d := make([]int, N)
	for i := 0; i < N; i++ {
		d[i] = INF
	}
	done := make([]bool, N)
	pq := &PQ{}
	heap.Init(pq)
	d[0] = 0
	heap.Push(pq, Node{0, 0})
	for pq.Len() > 0 {
		cur := heap.Pop(pq).(Node).id
		if done[cur] {
			continue
		}
		done[cur] = true
		for i := 0; i < len(E[cur]); i++ {
			to, cost := E[cur][i].to, E[cur][i].cost+d[cur]
			if !done[to] && cost < d[to] {
				d[to] = cost
				heap.Push(pq, Node{to, cost})
			}
		}
	}

	for i := 0; i < N; i++ {
		fmt.Fprintln(wtr, i, d[i])
	}
	wtr.Flush()
}

C++: #include <bits/stdc++.h>
using namespace std;
static const int INF   = (1 << 21);
static const int WHITE = 0;
static const int GRAY  = 1;
static const int BLACK = 2;
static const int NIL   = -1;
static const int MAX   = 10000;

int n;
vector<vector<pair<int, int>>> M(MAX);

void dijstra(int s) {
  vector<int> color(n, WHITE);
  vector<int> d(n, INF);
  d[s] = 0;
  priority_queue<pair<int, int>> pq;
  pq.push(make_pair(0, 0));

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

    int u    = tmp.second;
    color[u] = BLACK;
    if (d[u] < tmp.first * (-1)) continue;

    int size = M[u].size();
    for (int i = 0; i < size; i++) {
      int v = M[u][i].second;
      if (color[v] == BLACK) continue;

      if (d[u] + M[u][i].first < d[v]) {
        d[v]     = d[u] + M[u][i].first;
        color[v] = GRAY;
        pq.push(make_pair(d[v] * (-1), v));
      }
    }
  }
  int res = 0;
  for (int i = 0; i < n; i++) {
    cout << i << " " << d[i] << endl;
  }
}

int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    int id, k;
    cin >> id >> k;
    for (int j = 0; j < k * 2; j += 2) {
      pair<int, int> p;
      cin >> p.second >> p.first;
      M[id].push_back(p);
    }
  }
  dijstra(0);
}

C++: #include <functional>
#include <queue>
#include <stdio.h>
#include <utility>
#include <vector>

static const int MAX = 10000;
static const int INFINITY = 1 << 20;
static const int WHITE = 0;
static const int GRAY  = 1;
static const int BLACK = 2;

static int n;
static std::vector<std::pair<int, int> > adj[MAX];

void dijkstra()
{
    std::priority_queue<std::pair<int, int>, std::vector<std::pair<int, int>>, std::greater<std::pair<int, int>> > PQ;
    int color[MAX];
    int d[MAX];

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

    d[0] = 0;
    PQ.push(std::make_pair(0, 0));
    color[0] = GRAY;

    while (!PQ.empty()) {
        std::pair<int, int> f = PQ.top();
        PQ.pop();
        int u = f.second;
        color[u] = BLACK;
    
        if (d[u] < f.first)
            continue;

        for (int i = 0; i < adj[u].size(); i++) {
            int v = adj[u][i].first;
            if (color[v] == BLACK)
                continue;
            if (d[v] > d[u] + adj[u][i].second) {
                d[v] = d[u] + adj[u][i].second;
                PQ.push(std::make_pair(d[v], v));
                color[v] = GRAY;
            }
        }
    }

    for (int i = 0; i < n; i++) {
        printf("%d %d\n", i, (d[i] == INFINITY) ? -1 : d[i]);
    }
}

int main()
{
    scanf("%d", &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(std::make_pair(v, c));
        }
    }
    
    dijkstra();
    return 0;
}

C++: #include <vector>
#include <iostream>
#include <algorithm>
#include <limits>
#include <queue>

using namespace std;
using graph = vector<vector<int>>;


struct edge {
    int src;
    int dst;
    int weight;

    edge(int src, int dst, int w) : src(src), dst(dst), weight(w) {}
};

bool operator < (const edge &a, const edge &b) {
  return a.weight > b.weight;
}


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

    graph G(n, vector<int>(n, -1));
    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[u][v] = c;
        }
    }

    // Dijkstra's algorithm (with pritority queue)
    vector<int> d(n, -1);
    vector<bool> visited(n, false);
    priority_queue<edge> Q;

    Q.push(edge(-1, 0, 0));
    while (!Q.empty()) {
        auto e = Q.top(); Q.pop();
        if (visited[e.dst])
            continue;
        d[e.dst] = e.weight;
        visited[e.dst] = true;

        int i = e.dst;
        int minw = numeric_limits<int>::max();
        for (int j = 0; j < n; ++j) {
            if (visited[j] || G[i][j] < 0)
                continue;
            int w = G[i][j] + d[i];
            Q.push(edge(i, j, w));
        }
    }

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

    return 0;
}