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 <iostream>
#include <algorithm>
#include <queue>
 using namespace std;
 static const int WHITE = 0;
 static const int GRAY = 1;
 static const int BLACK =2;
 static const int MAX = 10000;
 static const int INFTY = (1<<20);
 
 int n;
 vector<pair<int,int> >adj[MAX];
 
 void dij(){
 	priority_queue<pair<int,int> >PQ;
 	int color[MAX];
 	int d[MAX];
 	for(int i=0;i<n;i++){
 		color[i] = WHITE;
 		d[i] = INFTY;
 	}
 	
 	d[0] = 0;
 	PQ.push(make_pair(0,0));
 	color[0] = GRAY;
 	while(!PQ.empty()){
 		pair<int ,int> f =PQ.top();
 		PQ.pop();
 		int u= f.second;
 		
 		color[u] = GRAY;
 		
 		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[v]>d[u]+adj[u][v].second){
 				d[v] = d[u]+adj[u][v].second;
 				PQ.push(make_pair(d[v]*(-1),v));
 				color[v] = GRAY;
 			}
 			
 		}
 	}
 	
 	for(int i=0;i<n;i++){
 		cout<<i<<" "<<(d[i]==INFTY?-1:d[i])<<endl; 
 	}
 }
 
 int main(){
 		cin>>n;
 	
 	int k,u,c,v;
 	for(int i=0;i<n;i++){
 		cin>>u>>k;
 		for(int j=0;j<k;j++){
 			cin>>c>>v;
 		adj[u].push_back(make_pair(c,v));
 		}
 	}
 	dij();
 	return 0;
 }

C++: #include <bits/stdc++.h>
using namespace std;
struct Graph{
  using seen_t=size_t; using ver_t=size_t; using edge_t=pair<ver_t,seen_t>;
  const seen_t NO=1e9;
  vector<seen_t> seen;
  vector<vector<edge_t>> edge;
  Graph(size_t n): seen(n,NO), edge(n) {}

  void search(ver_t v0){
    seen[v0]=0;
    priority_queue<pair<seen_t,ver_t>,vector<pair<seen_t,ver_t>>,greater<pair<seen_t,ver_t>>> que; que.push(make_pair(0,v0)); // dijkstra
    ver_t curv; seen_t alt;
    while(!que.empty()){
      curv=que.top().second; que.pop(); // dijkstra
      for(const auto& nextv:edge[curv]){
        alt=seen[curv]+nextv.second;
        if(seen[nextv.first]>alt && alt<NO){
          seen[nextv.first]=alt;
          que.push(make_pair(alt,nextv.first)); // dijkstra
        }
      }
    }
  }
};
ostream& operator<<(ostream& os, const Graph& x){
  for(size_t i=0; i<x.edge.size(); ++i){
    cout<<(i)<<' '<<x.seen[i]<<'\n';
  }
  return os;
}
int32_t main(){
  ios::sync_with_stdio(false); cin.tie(0);
  size_t n; cin>>n;
  Graph graph(n);
  size_t u,k,v,c;
  for(size_t i=0; i<n; ++i){
    cin>>u>>k;
    graph.edge[u].resize(k);
    for(size_t j=0; j<k; ++j){
      cin>>v>>c; graph.edge[u][j]=make_pair(v,c);
    }
  }
  graph.search(0);
  cout<<graph;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cassert>
#include <string>
#include <cstring>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>

using namespace std;

// ---------------------
// repetition
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)

// debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

// ---------------------
#define INF (1 << 21)
typedef long long ll;

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

  vector<int> V[n];
  // int E[n][n];
  map<pair<int, int>, int> E;
  int d[n];
  int visited[n];

  priority_queue<pair<int, int> , vector<pair<int, int> >, greater<pair<int, int> > > Q;

  REP(i, n) {
    d[i] = INF;
    visited[i] = 0;
  }

  REP(_, n) {
    int u, k;
    cin >> u >> k;
    REP(__, k) {
      int v, c;
      cin >> v >> c;
      V[u].push_back(v);
      E[make_pair(u, v)] = c;
    }
  }

  d[0] = 0;
  Q.push(make_pair(d[0], 0));
  REP(_, n) {
    // int minv = -1;
    // int mincost = INF;
    // REP(v, n) {
    //   if (!visited[v] && d[v] < mincost) {
    //     minv = v;
    //     mincost = d[v];
    //   }
    // }
    int mincost = Q.top().first;
    int minv = Q.top().second;

    visited[minv] = 1;
    for (vector<int>::iterator it = V[minv].begin(); it != V[minv].end(); it++) {
      if (E[make_pair(minv, *it)] < INF && d[minv] + E[make_pair(minv, *it)] < d[*it]) {
        d[*it] = d[minv] + E[make_pair(minv, *it)];
        Q.push(make_pair(d[*it], *it));
      }
    }
  }

  REP(i, n) {
    cout << i << " " << d[i] << endl;
  }
  return 0;
}