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 _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<cstdio>
#include<string>
#include<algorithm>
#include<cmath>
using namespace std;

#define REP(i,n) for(int i=0;(i)<(n);(i)++)

static const int INFTY = (1 << 29);
static const int WHITE = 0; //?????¢?´¢
static const int GRAY = 1; //??¢?´¢??????
static const int BLACK = 2; //?¨??????????

int n, M[101][101];

void dijkstra(void) {
	int dist[101]; //?§????????????????i????§????????????????????????????
	int color[101]; //?¨??????¶???(???or??°or???)

	//?????????????????§?????????????¨??????¶???????????§?????????
	REP(i, n) {
		dist[i] = INFTY;
		color[i] = WHITE;
	}

	dist[0] = 0; //?§????0??????0?????§???????????????0
	color[0] = GRAY; //0?????¢?´¢??????	

	//?????¢?´¢???????????????????????????????°??????????????§????????????????????????´??°????????????
	int minCost;
	while (true) {
		minCost = INFTY; //????°??????????????????????
		int minNode = -1; //????°?????????????????????????????????????
		REP(i, n) {
			if (minCost > dist[i] && color[i] != BLACK) {
				minNode = i;
				minCost = dist[i];
			}
		}
		if (minNode == -1) break; //-1???????????¨???????????¨????????????????????????????????£?????¨???????????¨

		color[minNode] = BLACK; //????°??????????????????????????§??????????????¨???????????????????

		//??¢?´¢????????????????????????????????´??°??????
		REP(v, n) {
			if (color[v] != BLACK && M[minNode][v] != INFTY) {
				if (dist[v] > dist[minNode] + M[minNode][v]) {
					dist[v] = dist[minNode] + M[minNode][v];
					color[v] = GRAY;
				}
			}
		}
	}
	
	REP(i, n) {
		cout << i << " " << (dist[i] == INFTY ? -1 : dist[i]) << endl;
	}

}

int main() {
	cin >> n;

	//??£??\???????????????????????§?????????
	REP(i, n) {
		REP(j, n) {
			M[i][j] = INFTY;
		}
	}

	//??£??\??????????????????
	int u, k, v, c;
	REP(i, n) {
		cin >> u >> k;
		REP(j, k) {
			cin >> v >> c;
			M[u][v] = c;
		}
	}

	dijkstra();

	
	return 0;
}

C++: #include<cstdio>
#include<iostream>
#define INF 200001 
using namespace std;
int main(){
 int u,k,C,V,A[1000][1000],D[1000][1000],n;
  scanf("%d",&n);
   for(int i=0;i<n;i++)for(int j=0;j<n;j++)D[i][j] = INF;
  for(int i=0;i<n;i++){
      scanf("%d %d",&u,&k);    
      for(int j=0;j<k;j++){
    scanf("%d %d",&V,&C);
    D[u][V] = C;
      }    
  }
  for(int i=0;i<n;i++)D[i][i] = 0;
  for(int k=0;k<n;k++)for(int i=0;i<n;i++)for(int j=0;j<n;j++)D[i][j]= min(D[i][j],D[i][k] + D[k][j]);
  for(int i=0;i<n;i++)printf("%d %d\n",i,D[0][i]);
  return 0;
}

C++: #include <iostream>
#include <vector>
#include <queue>
using namespace std;


int main() {
    int N; cin >> N;
    int u, k, v, c; 
    const int inf = 100000000;
    

    vector<pair<int, int> > G[N];
    for (int i = 0; i < N; ++i) {
        cin >> u >> k;
        for (int j = 0; j < k; ++j) {
            cin >> v >> c;
            G[u].push_back(make_pair(c, v));
        }
    }

    int dist[N]; 
    priority_queue<pair<int, int> > que;

    for (int i = 0; i < N; ++i) {
        if (i) dist[i] = inf;
        else dist[i] = 0;
    }
    que.push(make_pair(0, 0));

    while (!que.empty()) {
        pair<int, int> f = que.top(); que.pop();
        int cur_cost = f.first*(-1);
        int cur_vtx = f.second;

        if (dist[cur_vtx] < cur_cost) continue;

        for (int i = 0; i < G[cur_vtx].size(); ++i) {
            int next_cost = G[cur_vtx][i].first;
            int next_vtx = G[cur_vtx][i].second;

            if (dist[next_vtx] > cur_cost + next_cost) {
                dist[next_vtx] = cur_cost + next_cost;
                que.push(make_pair(dist[next_vtx]*(-1), next_vtx));
            }
        }   
    }

    for (int v = 0; v < N; ++v) cout << v<< " " << dist[v] << endl;

    return 0;
}

C++: #include <iostream>

using namespace std;

static const int MAX = 100;
static const int INF = 1 << 30;
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] = INF;
        color[i] = WHITE;
    }

    d[0] = 0;

    while (true){
        minv = INF;
        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] !=INF){
                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] == INF ? -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] = INF;
        }
    }

    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;
}