Go: package main

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

type Node struct {
	Id int
	Dis int
}

type PriorityQueue []*Node

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

func (pq PriorityQueue) Less(i, j int) bool {
	return pq[i].Dis < pq[j].Dis
}

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

func (pq *PriorityQueue) Push(x interface{}) {
	*pq = append(*pq, x.(*Node))
}

func (pq *PriorityQueue) Pop() interface{} {
	n := len(*pq)
	pop := (*pq)[n-1]
	*pq = (*pq)[0:n-1]
	return pop
}

func main() {
	var n int
	fmt.Scan(&n)

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

	g := make([][]int, n)
	c := make([][]int, n)
	pq := make(PriorityQueue, 0, n)
	d := make([]int, n)
	for i := 0; i < n; i++ {
		sc.Scan()
		u, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		k, _ := strconv.Atoi(sc.Text())
		g[u] = make([]int, k)
		c[u] = make([]int, k)
		for j := 0; j < k; j++ {
			sc.Scan()
			g[u][j], _ = strconv.Atoi(sc.Text())
			sc.Scan()
			c[u][j], _ = strconv.Atoi(sc.Text())
		}

		if u == 0 {
			d[u] = 0
		} else {
			d[u] = 1 << 30
		}
		pq.Push(&Node{u, d[u]})
	}
	heap.Init(&pq)

	for pq.Len() > 0 {
		node := heap.Pop(&pq).(*Node)
		for i := 0; i < len(g[node.Id]); i++ {
			nextId := g[node.Id][i]
			nextDis := node.Dis + c[node.Id][i]
			if nextDis < d[nextId] {
				d[nextId] = nextDis
				heap.Push(&pq, &Node{nextId, nextDis})
			}
		}
	}

	wr := bufio.NewWriter(os.Stdout)
	for i := 0; i < n; i++ {
		wr.WriteString(strconv.Itoa(i))
		wr.WriteString(" ")
		wr.WriteString(strconv.Itoa(d[i]))
		wr.WriteString("\n")
	}
	wr.Flush()
}

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;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <bitset>
#include <map>
#include <tuple>
#include <unordered_map>
#include <list>
#include <numeric>
#include <utility>
#include <iterator>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <climits>
#include <ctime>
#include <cassert>
#include <random>

#define INF 1000000000
#define LINF 9000000000000000000
#define mod  1000000007

#define rep(i,n) for(int i=0;i<int(n);i++)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define REP(i,a,b) for(int i=(a);i<int(b);i++)
#define all(x) (x).begin(),x.end()
#define pb push_back
#define mp make_pair

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef pair<int,int> pi;

int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int ddx[8]={-1,-1,0,1,1,1,0,-1};
int ddy[8]={0,1,1,1,0,-1,-1,-1};
bool debug=false;

/*---------------------------------------------------*/

struct Edge{
  int to;
  ll cost;
  Edge(int t, int c){
    to = t;
    cost = c;
  }
};

typedef pair<ll, ll> P;

int d[10005];
vector<Edge> G[10005];

void dijkstra(int s){
  ll inf = LLONG_MAX / 100;
  priority_queue<P, vector<P>, greater<P>> que; 
  for(int i = 0; i < 10005; i++){
    d[i] = inf;
  }

  d[s] = 0;
  que.push(P(0, s));
  while(que.size()){
    P p = que.top(); que.pop();
    int v = p.second;
    if(d[v] < p.first) continue;
    for(int i = 0; i < G[v].size(); i++){
      Edge e = G[v][i];
      if(d[e.to] > d[v] + e.cost){
	d[e.to] = d[v] + e.cost;
	que.push(P(d[e.to], e.to));
      }
    }
  }
}

int main(){
  int n, u, k, c, v;
  cin >> 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(Edge(v, c));
    }
  }

  dijkstra(0);
  for(int i = 0; i < n; i++){
    cout << i << " " << d[i] << endl;
  }
}

C++: #include <cstdio>
#include <iostream>
#include <cmath>
#include <ctype.h>
#include <string>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <map>
#include <queue>
#include <utility>
#include <vector>
#include <set>
#include <list>
#include <cstring>
#include <stack>

using namespace std;

#define mod 1000000007

int main()
{
	int n;
	cin >> n;
	int ans[101] = {};
	vector<vector<pair<int, int> > > graph(n + 1);
	for(int i = 0; i < n; i++){
		ans[i] = -1;
		int u, k;
		cin >> u >> k;
		for(int j = 0; j < k; j++){
			int v, c;
			cin >> v >> c;
			graph[u].push_back(make_pair(v, c));
		}
	}
	priority_queue<pair<int, int> > qu;
	qu.push(make_pair(0, 0));
	ans[0] = 0;
	while(!qu.empty()){
		int nowd = -(qu.top()).first;
		int nownode = (qu.top()).second;
		qu.pop();
		for(int i = 0; i < graph[nownode].size(); i++){
			int node = graph[nownode][i].first;
			int next = nowd + graph[nownode][i].second;
			if(ans[node] < 0 || ans[node] > next){
				ans[node] = next;
				qu.push(make_pair(-next, node));
			}
		}
	}
	for(int i = 0; i < n; i++){
		cout << i << " " << ans[i] << endl;
	}
}