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++: #include <iostream>
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 solve(void) {
    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(true) {
        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 i = 0; i < n; ++i) {
            if(color[i] != BLACK && M[u][i] != INFTY) {
                if(d[i] > d[u] + M[u][i]) {
                    d[i] = d[u] + M[u][i];
                    color[i] = GRAY;
                }
            }
        }
    }
    for(int i = 0; i < n; ++i) {
        cout << i << ' ' << (d[i] == INFTY ? -1 : d[i]) << endl;
    }
}

int main(void) {
    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;
        }
    }
    
    solve();
    
    return 0;
}

C++: #include<bits/stdc++.h>
#define INF 1e9
#define MAX_V 100
using namespace std;
int cost[MAX_V][MAX_V];
int d[MAX_V];
bool used[MAX_V];
int V;
void dijkstra(int s){
    fill(d,d+V,INF);
    fill(used,used+V,false);
    d[s]=0;
    
    while(true){
        int v=-1;
        for(int u=0;u<V;u++){
            if(!used[u] && (v == -1 || d[u] < d[v])){
                v = u;
            }
        }
        
        if(v == -1) break;
        
        used[v] = true;
        
        for(int u=0;u<V;u++){
            d[u] = min(d[u],d[v]+cost[v][u]);
        }
    }
    
    for(int i=0;i<V;i++) cout<<i<<" "<<d[i]<<endl;

    return ;
}

int main(){
    cin>>V;
    int u,k,v,c;

    for(int i=0;i<V;i++)
        for(int j=0;j<V;j++) cost[i][j]=INF;
    
    for(int i=0;i<V;i++){
        cin>>u>>k;
        for(int j=0;j<k;j++){
            cin>>v>>c;
            cost[u][v]=c;
        }
    }
    
    dijkstra(0);
    
    return 0;
}

C++: #include<iostream>
#include<iomanip>
#include<queue>
#include<string>
#include<stack>
#include<cstdio>
#include<cstdlib>
#include<cmath>
#include<cstring>
#include<cassert>
#include<ctime>
#include<algorithm>
#include<utility>
#include<map>
#include<set>
#include<vector>
#include<functional>

using namespace std;

#ifdef DEBUG
#define dprintf      printf
#define dout(x)      cout<<#x" = "<<(x)<<endl
#define darray(x,n)    {int i;rep(i,n)cout<<#x"["<<i<<"] = "<<*((x)+i)<<endl;}
#define dloop(i,s,g) for((i)=(s);(i)<(g);(i)++)
#define drep(i,n)    for((i)=0;(i)<(n);(i)++)
#define dstop()      scanf("%*c")
#else
#define dprintf      (1)?0:printf
#define dout(x)
#define darray(x,n)
#define dloop(i,s,g) if(1){}else
#define drep(i,n)    if(1){}else
#define dstop()      if(1){}else
#endif

#define F    first
#define S    second
#define pb   push_back
#define mp   make_pair

#define loop(i,s,g) for((i)=(s);(i)<(g);(i)++)
#define rep(i,n)    for((i)=0;(i)<(n);(i)++)
#define all(x)      (x.begin(),x.end())
#define in(T,...) T __VA_ARGS__; impl(__VA_ARGS__);
#define array(T,id,n) T id[n]; rep(i,n)cin>>id[i];

//#define int long long;
#ifndef int
#define INF  (0x7fffffff)
#else
#define LINF (0x7fffffffffffffff)
#endif

typedef long long           ll;
typedef unsigned            ui;
typedef unsigned long long  ull;
typedef pair<int,int>       i_i;
typedef pair<ll,int>        ll_i;
typedef pair<ll,ll>         ll_ll;
typedef pair<double,int>    d_i;
typedef pair<double,double> d_d;

void impl(){};
template <typename T,typename... TS >
void impl(T &head,TS &... tail)
{
  cin>>head;
  impl(tail ...);
}

typedef struct edge
{
  int to;
  int cost;
}Edge;
int V;
#define MAX_V (1000)
vector<Edge> G[MAX_V];
int d[MAX_V];

void djikstra(int s)
{
  int i;
  priority_queue<i_i,vector<i_i>,greater<i_i> > q;
  fill(d,d+V,INF);
  d[s]=0;
  q.push(i_i(0,s));
  while(!q.empty())
    {
      i_i p=q.top();
      q.pop();
      int v=p.S;
      if(d[v]<p.F)
	continue;
      rep(i,G[v].size())
	{
	  Edge e=G[v][i];
	  if(d[e.to]>d[v]+e.cost)
	    {
	      d[e.to]=d[v]+e.cost;
	      q.push(i_i(d[e.to],e.to));
	    }
	}
    }
}

signed main(void)
{
  int n;
  int i,j;
  int u;
  int k;
  Edge e;

  cin>>n;
  rep(i,n)
    {
      cin>>u>>k;
      rep(j,k)
	{ 
	  cin>>e.to>>e.cost;
	  G[j].pb(e);
	}
    }
  djikstra(0);
  rep(i,n)
    {
      cout<<i<<" "<<d[i]<<endl;
    }
  return 0;
}