Go: package main

import (
	"bufio"
	"container/heap"
	"fmt"
	"os"
	"strconv"
)

//make priority queue
type Item struct {
	id       int
	priority int // this state is priority and distans from start
	index    int
}

type PriorityQueue []*Item

func (pq PriorityQueue) Len() int { return len(pq) }

// we want the ascending-priority-queue.
// So we use less than here.
func (pq PriorityQueue) Less(i, j int) bool {
	return pq[i].priority < pq[j].priority
}

func (pq PriorityQueue) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
	pq[i].index = j
	pq[j].index = i
}

func (pq *PriorityQueue) Push(x interface{}) {
	n := len(*pq)
	item := x.(*Item)
	item.index = n
	*pq = append(*pq, item)
}

func (pq *PriorityQueue) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	item.index = -1 //for safety
	*pq = old[0 : n-1]
	return item
}

func (pq *PriorityQueue) update(dist int, id int) {
	for _, i := range *pq {
		if i.id == id {
			if i.priority > dist {
				i.priority = dist
			}
		}
	}
}

// the main code
func nextInt(sc *bufio.Scanner) int {
	sc.Scan()
	n, _ := strconv.Atoi(sc.Text())
	return n
}

func dikstra(dist *[][]int, n int) *[]int {
	// preparate priority queue
	inf := 1 << 30
	pq := make(PriorityQueue, n)
	shortests := make([]int, n)
	for i := 0; i < n; i++ {
		pq[i] = &Item{
			id:       i,
			priority: inf,
			index:    i,
		}

		shortests[i] = inf
	}
	pq[0].priority = 0
	shortests[0] = 0
	heap.Init(&pq)

	for pq.Len() > 0 {
		item := heap.Pop(&pq).(*Item)
		shortests[item.id] = item.priority
		for id, d := range (*dist)[item.id] {
			if d != -1 {
				pq.update(item.priority+d, id)
			}
		}
		heap.Init(&pq)
	}
	return &shortests
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	// init
	n := nextInt(sc)
	dist := make([][]int, n)
	for i := 0; i < n; i++ {
		dist[i] = make([]int, n)
		for j := 0; j < n; j++ {
			dist[i][j] = -1
		}
	}

	// std Input
	for i := 0; i < n; i++ {
		u := nextInt(sc)
		k := nextInt(sc)
		for j := 0; j < k; j++ {
			v, c := nextInt(sc), nextInt(sc)
			dist[u][v] = c
		}
	}

	shortests := dikstra(&dist, n)
	for i, d := range *shortests {
		fmt.Printf("%d %d\n", i, d)
	}
}

C++: #define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
using namespace std;

const int NOTV = 0;
const int VIST = 1;
const int NMAX = 10000;
//const int VMAX = 2000;
const int NILL = -1;
const int INF = 1 << 21;
//int a[NMAX][NMAX];  //??£??\??????
int n;
vector<pair<int, int>> adj[NMAX];

void dijkstra() {
	int d[NMAX];
	int vst[NMAX];
	priority_queue<pair<int, int>> pq;
	for (int i = 0; i < n; i++) {
		vst[i] = NOTV;
		d[i] = INF;
	}
	d[0] = 0;
	pq.push(make_pair(d[0], 0));
	while (not pq.empty()) {
		pair<int, int> f = pq.top(); pq.pop();
		int u = f.second;
		vst[u] = VIST;
		if (d[u] < f.first*(-1)) continue;
		for (int i = 0; i < adj[u].size(); i++) {
			int v = adj[u][i].first;
			if (vst[v] == NOTV) {
				if (d[u] + adj[u][i].second < d[v]) {
					d[v] = d[u] + adj[u][i].second;
					pq.push(make_pair(d[v] * (-1), v));
				}
			}
		}
	}
	for (int i = 0; i < n; i++) {
		cout << i << ' ' << d[i] << endl;
	}
}

int main() {
	cin >> n;
	int k, u, v, c;
	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		for (int j = 0; j < k; j++) {
			cin >> v >> c;
			adj[u].push_back(make_pair(v, c));
		}
	}
	dijkstra();
	return 0;
}

C++: //
//  main.cpp
//
//
//  Created by ???????????? on 2017/10/23.
//  Copyright ?? 2017 ????????????. All rights reserved.
//

#include <iostream>
#include <stdio.h>
#include <queue>
#include <algorithm>


#define n_max 100
#define WHITE 0
#define GRAY 1
#define BLACK 2
#define INFTY (1<<20)

using namespace std;

int n, M[n_max][n_max], color[n_max], d[n_max], p[n_max];

void init(){
    int i, j, id, num, node;
    scanf("%d", &n);
    for(i = 0; i < n; i++){
        for(j = 0; j < n; j++){
            M[i][j] = INFTY;
        }
    }
    
    
    for(i = 0; i < n; i++){
        scanf("%d %d", &id, &num);
        for(j = 0; j < num; j++){
            scanf("%d", &node);
            scanf("%d", &M[id][node]);
        }
        color[i] = WHITE;
        d[i] = INFTY;
    }
}


int main(int argc, const char * argv[]) {
    init();
    //    std::cout << "Hello, World!\n";
    return 0;
}

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

#define MAX 10000
#define INFTY (1 << 20)
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n;
vector<pair<int, int> > adj[MAX];

void solve(void) {
    priority_queue<pair<int, int> > PQ;
    int color[MAX];
    int d[MAX];
    for(int i = 0; i < n; ++i) {
        d[i] = INFTY;
        color[i] = WHITE;
    }
    
    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] = BLACK;
        
        if(d[u] < f.first * (-1)) continue;
        
        for(int i = 0; i < adj[u].size(); ++i) {
            int v = adj[u][i].first;
            if(color[v] == BLACK) continue;
            if(d[v] > d[u] + adj[u][i].second) {
                d[v] = d[u] + adj[u][i].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(void) {
    int k, u, v, c;
    
    cin >> n;
    for(int i = 0; i < n; ++i) {
        cin >> u >> k;
        for(int j = 0; j < k; ++j) {
            cin >> v >> c;
            adj[u].push_back(make_pair(v, c));
        }
    }
    
    solve();
    
    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <climits>
#include <cmath>
#include <algorithm>
#include <utility>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#define MAX 10000
#define INFTY 1<<30 // 2^30
using namespace std;
typedef long long llong;
static const int NIL = -1;
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;

int n;
vector<pair<int, int> > adj[MAX];

void dijkstra()
{
  priority_queue<pair<int, int> > PQ;
  int color[MAX];
  int d[MAX];
  for(int i = 0; i < n; i++)
  {
    d[i] = INFTY;
    color[i] = WHITE;
  }
  d[0] = 0;
  PQ.push(make_pair(0,0));
  while(!PQ.empty())
  {
    pair<int, int> f = PQ.top(); PQ.pop();
    int u = f.second;
    color[u] = BLACK;
    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][j].second)
      {
        d[v] = d[u] + adj[u][j].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, c, u, v;
  for(int i = 0; i < n; i++)
  {
    cin >> u >> k;
    for(int j = 0; j < k; j++)
    {
      cin >> v >> c;
      adj[u].push_back(make_pair(v, c));
    }
  }
  dijkstra();
  return 0;
}

C++: # -*- coding: utf-8 -*-
from heapq import heapify, heappop, heappush

N = int(input())
INF = float("inf")
d = [INF for n in range(N)]
d[0] = 0
adj = [[] for _ in range(N)]

searched = [False for _ in range(N)]
searched[0] = True

for n in range(N):
    inp = tuple(map(int, input().split()))
    assert n == inp[0]
    for i in range(inp[1]):
        adj[n] = list(zip(inp[2::2], inp[3::2]))

heap = [[0, 0]]

while len(heap):
    pcost, p = heappop(heap)
    searched[p] = True
    
    if d[p] < pcost:
        continue
    
    for v, c in adj[p]:
        if not searched[v]:
            new_cost = pcost + c
            if new_cost < d[v]:
                d[v] = new_cost
                heappush(heap, [new_cost, v])

for n in range(N):
    print("{} {}".format(n, d[n]))