Go: package main

import (
	"bufio"
	"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
type Node struct {
	cost int
	done bool
}

type Edge struct {
	to, cost int
}

const INF = 1 << 60

func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	nodes := make([]Node, N)
	for i := 0; i < N; i++ {
		nodes[i].cost = INF
	}
	E := make([][]Edge, N)
	for i := 0; i < N; i++ {
		id, k := sc.nextInt(), sc.nextInt()
		for j := 0; j < k; j++ {
			to, cost := sc.nextInt(), sc.nextInt()
			E[id] = append(E[id], Edge{to, cost})
		}
	}
	nodes[0].cost = 0
	for {
		cur := 0
		minCost := INF
		for i := 0; i < N; i++ {
			n := nodes[i]
			if !n.done && n.cost < minCost {
				cur = i
				minCost = n.cost
			}
		}
		if minCost == INF {
			break
		}
		nodes[cur].done = true
		for i := 0; i < len(E[cur]); i++ {
			to, cost := E[cur][i].to, E[cur][i].cost+nodes[cur].cost
			if !nodes[to].done && cost < nodes[to].cost {
				nodes[to].cost = cost
			}
		}
	}

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

C++: #define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define USE_LLONG_AS_INT
#ifdef USE_LLONG_AS_INT
#define int long long
#define inf (1ll<<60)
#else
#define inf (1<<30)
#endif
#define rep(i,n) for(int i=0;i<(n);i++)
#define Rep(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,a,b) for(int i=(a);i<=(b);i++)
#define rev(i,n) for(int i=(n)-1;i>=0;i--)
#define vi vector<int>
#define vvi vector<vi>
#define pb push_back
#define eb emplace_back
#define pi pair<int,int>
#define vp vector<pair<int,int>>
#define mp make_pair
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define MEMSET(a) memset(a,0,sizeof(a))
#define Yes(f) cout<<(f?"Yes":"No")<<endl
#define yes(f) cout<<(f?"yes":"no")<<endl
#define YES(f) cout<<(f?"YES":"NO")<<endl
#define SORT(v) sort(all(v))
#define RSORT(v) sort(all(v), greater<int>())

using namespace std;

const int mod=1e9+7;
const string sp=" ";

void run();

void init() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout<<fixed<<setprecision(12);
}

signed main(){
    init();
    run();
    return 0;
}

int n;
vector<vp> g;

void solve(){
    vi d(n,inf);
    priority_queue<pi,vp,greater<pi>> q;
    d[0]=0;
    q.push({0,0});
    while(!q.empty()){
        pi p=q.top();
        q.pop();
        int v=p.se;
        if(d[v]<p.fi)continue;
        for(pi e:g[v]){
            if(d[e.se]>d[v]+e.fi){
                d[e.se]=d[v]+e.fi;
                q.push({d[e.se],e.se});
            }
        }
    }
    rep(i,n){
        cout<<i<<sp<<d[i]<<endl;
    }
}

void run(){
    cin>>n;
    g.resize(n);
    rep(i,n){
        int u,k;
        cin>>u>>k;
        rep(j,k){
            int v,c;
            cin>>v>>c;
            g[u].eb(pi(c,v));
        }
    }
    solve();
}

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, N[MAX][MAX];

void dijkstra(){
  int minv;
  int d[MAX],color[MAX];
  int i=0;

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

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

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

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

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

  dijkstra();

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

  M[u][v] = c;
  }
 }
  dijkstra();
   return 0;
}

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

struct Edge {
	int to, weight;
};

int main()
{
	int n, u, k, v, c, distance[100]{}, upd_num = 1;
	bool must_update[100]{ 1 };
	std::vector<Edge> dest[100];

	std::cin >> n;
	for (int i = 0; i < n; ++i)
	{
		std::cin >> u >> k;
		for (int j = 0; j < k; ++j)
		{
			std::cin >> v >> c;
			dest[u].push_back({ v, c });
		}
		if (i)
			distance[i] = 2000000000;
	}

	while (upd_num)
	{
		for (int i = 0; i < n; i++)
		{
			if (!must_update[i]) continue;

			must_update[i] = false;
			upd_num--;
			for (auto e : dest[i])
			{
				int tmp = distance[i] + e.weight;
				if (tmp < distance[e.to])
				{
					distance[e.to] = tmp;
					must_update[e.to] = true;
					upd_num++;
				}
			}
		}
	}

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

	return 0;
}