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++: #include <stdio.h>
#include <string.h>
#include <algorithm>
#include <iostream>
#include <string>
#include <math.h>
#include <ctype.h>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <functional>
using namespace std;

typedef long long ll;
typedef pair<ll, int> pp;
#define mp(a, b) make_pair(a, b)

struct edge {
	int v, w;
	int next;
	edge() {}
	edge(int v_, int w_, int n_) : v(v_), w(w_), next(n_) {}
};

int n, cnt;
int head[10001];
edge e[600000];
bool vis[10001];
ll dis[10001];

void init()
{
	cnt = 0;
	memset(head, -1, sizeof head);
}
void addedge(int u, int v, int w)
{
	e[++cnt] = edge(v, w, head[u]); head[u] = cnt;
}
void dijkstra(int s)
{
	for (int i = 0; i < n; i++)
		vis[i] = 0, dis[i] = ll(1e18);
	dis[s] = 0; vis[s] = 1;
	for (int i = head[s]; i != -1; i = e[i].next)
		dis[e[i].v] = e[i].w;
	while(1)
	{
		int idx = -1;
		ll dist = 1e18;
		for (int j = 0; j < n; j++)
			if (!vis[j] && dist > dis[j])
			{
				idx = j;
				dist = dis[j];
			}
		if (idx == -1)
			break;
		vis[idx] = 1;
		for (int j = head[idx]; j != -1; j = e[j].next)
		{
			int v = e[j].v;
			ll w = e[j].w;
			if (dis[v] > dis[idx] + w)
				dis[v] = dis[idx] + w, vis[v] = 0;
		}
	}
}

int id[10001];

int main()
{
	int s;
	while (scanf("%d", &n) == 1)
	{
		init();
		for (int i = 0; i < n; i++)
		{
			int u, k;
			scanf("%d%d", &u, &k);
			id[i] = u;
			if (u == 0)
				s = i;
			while (k--)
			{
				int v, w;
				scanf("%d%d", &v, &w);
				addedge(u, v, w);
			}
		}
		dijkstra(s);
		for (int i = 0; i < n; i++)
			printf("%d %lld\n", id[i], dis[i]);
	}
	return 0;
}

C++: // #define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define Graph vector< vector<P> >
typedef long long ll;
typedef pair<int, int> P;
const int INF = 1000000007;

int main(){
    int N;
    cin >> N;
    Graph M(N);
    rep(i, N){
        int u, k;
        cin >> u >> k;
        rep(j, k){
            int v, c;
            cin >> v >> c;
            M[u].push_back(P(v, c));
        }
    }

    vector<int> d(N, INF), p(N, -1);
    vector<bool> seen(N, false);
    d[0] = 0;

    while(1){
        int mincost = INF;
        int u;

        rep(i, N){
            if(!seen[i] && d[i] < mincost){
                mincost = d[i];
                u = i;
            }
        }

        if(mincost == INF) break;
        seen[u] = true;

        rep(i, M[u].size()){
            int v = M[u][i].first, c = M[u][i].second;
            if(!seen[v] && d[u] + c < d[v]){
                d[v] = d[u] + c;
                p[v] = u;
            }
        }
    }

    rep(i, N){
        cout << i << ' ' << d[i] << endl;
    }

}

C++: // Ref : https://book.mynavi.jp/ec/products/detail/id=35408

#include <iostream>
#include <algorithm>
#include <queue>
using namespace std;
static const int MAX = 10000;
static const int INFTY = (1 << 20);
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));
	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 (unsigned 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;
				// priority queue order is converted from descending to ascending with -1.
				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() {
	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));
		}
	}

	/*
	for (int i = 0; i < n; i++) {
		vector<pair<int, int> >::iterator begin = adj[i].begin();
		vector<pair<int, int> >::iterator end = adj[i].end();
		cout << i << " ";
		for (; begin != end; begin++) {
			cout << (*begin).first << " " << (*begin).second << " ";
		}
		cout << endl;
	}
	*/

	dijkstra();

	return 0;
}