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;
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,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;
    }
  }
  dijkstra();
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
using P = pair<int, int>;

const int INF = INT_MAX/2;

struct Edge{
  int to;
  int cost;
  Edge():to(0),cost(0){}
  Edge(int to, int cost):to(to),cost(cost){}
  bool operator<(const Edge& e)const{
    return cost < e.cost;
  }
};

void dijkstra(const int start, const vector< vector<Edge> >& G1, vector< vector<int> >& G2){
  for(int i = 0;  i < G2[start].size(); i++){
    G2[start][i] = INF;
  }

  G2[start][0] = 0;

  priority_queue< P > que; //cost, pos
  que.push(P(0, start));
  while(!que.empty()){
    P p = que.top(); que.pop();
    int pos = p.second;
    int cost = p.first;
    if(G2[start][pos] < cost) continue;
    for(int i = 0; i < G1[pos].size(); i++){
      int to = G1[pos][i].to;
      if(G2[start][to] > G2[start][pos] + G1[pos][i].cost){
        G2[start][to] = G2[start][pos] + G1[pos][i].cost;
        que.push(P(G2[start][to], to));
      }
    }
  }
}

int main(void){
  int n;
  cin >> n;
  vector< vector< Edge > >G(n);
  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].push_back(Edge(v, c));
    }
  }
  vector< vector<int> > ans(1, vector<int>(n));
  dijkstra(0, G, ans);
  for(int i = 0; i < n; i++) cout << i << " " << ans[0][i] << endl;

  return 0;
}

C++: #include <iostream>
#define N 100
#define INFINITY 2000000000
using namespace std;
int n,k,u,v,c,M[N][N],d[N],p[N],mincost,i,j;
string color[N];
void dijkstra(void);
int main(){
  cin >> n;
  for(i=0;i<n;i++){
    for(j=0;j<n;j++){
      M[i][j]=-1;
    }
  }
  for(i=0;i<n;i++){
    cin >> u;
    cin >> k;
    for(j=0;j<k;j++){
      cin >> v >> c;
      M[u][v]=c;
    }
  }
  dijkstra();
  return 0;
}
void dijkstra(){
  for(i=0;i<n;i++) color[i]="WHITE",d[i]=INFINITY;
  d[0]=0;
  p[0]=-1;
  while(1){
    mincost=INFINITY;
    for(i=0;i<n;i++){
      if(color[i]!="BLACK"&&d[i]<mincost){
	mincost=d[i];
	u=i;
      }
    }
    if(mincost==INFINITY) break;
    color[u]="BLACK";
    for(i=0;i<n;i++){
      if(color[i]!="BLACK"&&M[u][i]!=-1){
	if(d[u]+M[u][i]<d[i]){
	  d[i]=d[u]+M[u][i];
	  p[i]=u;
	  color[i]="GLAY";
	}
      }
    }
  }
  for(i=0;i<n;i++) cout << i << ' ' << d[i] << endl;
}

C++: #include <bits/stdc++.h>
#define rep(i,a) for(i=0;i<a;i++)
using namespace std;
static const int W = 0;
static const int B = 1;

void dijkstra(int n, vector<vector<int> > &M) {
    int i,u,min;
    vector<int> d(n);
    vector<int> p(n);
    vector<int> color(n);

    rep(i,n){
        d[i] = INT_MAX;
        p[i] = -1;
        color[i] = W;
    }
    d[0] = 0;
    while(true){
        min = INT_MAX;
        rep(i,n){
            if(min > d[i] && color[i] != B) {
                u = i;
                min = d[i];
            }
        }
        if(min == INT_MAX) break;
        color[u] = B;
        rep(i,n){
            if(color[i] != B && M[u][i] + d[u] < d[i]) {
                p[i] = u;
                d[i] = M[u][i] + d[u];
            }
        }
    }
    rep(i,n){
        cout << i << " " << d[i] << endl;
    }
}

int main(void) {
    int i,j,n,u,k,v;
    vector<vector<int> > M;
    cin >> n;
    M.resize(n);

    rep(i,n){
        M[i].resize(n);
    }
    rep(i,n){
        rep(j,n){
            M[i][j] = (1<<21);
        }
    }

    rep(i,n){
        cin >> u >> k;
        rep(j,k){
            cin >> v;
            cin >> M[u][v];
        }
    }
    dijkstra(n,M);
    return 0;
}