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>
#include <vector>
#include <map>
#include <unordered_map>
#include <queue>
#include <set>
#include <algorithm>
#include <string>
#include <math.h>
#include <limits.h>
#include <stack>
#include <complex>
#include <stdlib.h>
#include <stdio.h>
#include <functional>
#include <cfloat>
#include <math.h>
#include <numeric>
#include <string.h>
#include <sys/time.h>
#include <random>


#define fs first
#define sc second

using namespace std;

typedef long long ll;
typedef unsigned int uint;
typedef pair<ll, ll> P;

ll squareDis(P x, P y){
    return (x.fs - y.fs) * (x.fs - y.fs) + (x.sc - y.sc) * (x.sc - y.sc);
}

bool judgeAcute(P x, P y, P z){
    ll dis1 = squareDis(x, y);
    ll dis2 = squareDis(x, z);
    ll dis3 = squareDis(y, z);

    return dis1 + dis2 > dis3;

}

class Graph{
    struct edge{
        int vertice;
        ll weight;
    };

    vector<vector<edge>> g;
    unsigned int n;

public:
    Graph(unsigned int n): n{n}{
        g.resize(n);
    }

    void add_edge(int u, int v){
        g[u].emplace_back(edge{v, 1});
    };

    void add_edge(int u, int v, ll w){
        g[u].emplace_back(edge{v, w});
    }

    vector<edge>& get_edge(int v){
        return g[v];
    }

    unsigned int get_num_vertices(){
        return n;
    }

    vector<edge>& operator[](int v){
        return get_edge(v);
    }
};


/**
 *
 * @param s 始点
 * @param g グラフ
 * @return sから各頂点への距離
 */
vector<ll> dijkstra1(int s, Graph g, ll INF=LONG_LONG_MAX / 3){
    unsigned int n = g.get_num_vertices();
    vector<bool> used(n, false);
    vector<ll> d(n, INF);

    d[s] = 0;
    while(true){
        int v = -1;
        for(int u = 0; u < n; u++) {
            if (!used[u] && (v == -1 || d[u] < d[v])) {
                v = u;
            }
        }

        if(v == -1) break;

        used[v] = true;
        for(auto e: g[v]){
            d[e.vertice] = min(d[e.vertice], d[v] + e.weight);
        }
    }

    return d;
}


vector<ll> dijkstra2(int s, Graph g, ll INF=LONG_LONG_MAX / 3){
    typedef pair<ll, int> Ptmp;  // firstは最短距離、secondは頂点の番号

    unsigned int n = g.get_num_vertices();
    priority_queue<Ptmp, vector<Ptmp>, greater<Ptmp>> que;
    vector<ll> d(n, INF);

    d[s] = 0;
    que.push(Ptmp(d[s], s));

    while(!que.empty()){
        Ptmp p = que.top();   que.pop();
        int v = p.second;
        if(d[v] < p.first) continue;
        for(auto e: g[v]){
            if(d[e.vertice] > d[v] + e.weight){
                d[e.vertice] = d[v] + e.weight;
                que.push(Ptmp(d[e.vertice], e.vertice));
            }
        }
    }

    return d;
}



int main(){
    uint n;  cin >> n;
    Graph 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.add_edge(u, v, c);
        }
    }

    vector<ll> res = dijkstra2(0, g);
    for(int i = 0; i < n; i++){
        cout << i << " " << res[i] << endl;
    }
}


//int main(){
//    int n, m;   cin >> n >> m;
//
//    vector<vector<edge>> g(100);
//    vector<P> cor(n);
//
//    for(int i = 0; i < n; i++){
//        int x, y;   cin >> x >> y;
//        cor[i] = P(x, y);
//    }
//    for(int i = 0; i < m; i++){
//        int a, b, c;    cin >> a >> b >> c;
//        a--; b--;
//        g[a].emplace_back(edge{c, b});
//        g[b].emplace_back(edge{c, a});
//    }
//
//    vector<vector<edge>> g2;
//    map<P, int> mp;
//    g2.emplace_back(vector<edge>(0));
//    int n2 = 0;
//    mp[P(0, 0)] = n2++;
//
//    for(int i = 0; i < n; i++){
//        for(auto v: g[i]){
//            g2.emplace_back(vector<edge>(0));
//            mp[P(i, v.v)] = n2++;
//        }
//    }
//
//    for(int i = 0; i < n; i++){
//        for(auto v: g[i]){
//            for(auto u: g[i]){
//                if(!judgeAcute(cor[i], cor[u.v], cor[v.v])){
//                    g2[mp[P(i, v.v)]].emplace_back(edge{u.w, mp[P(u.v, i)]});
//                }
//            }
//        }
//    }
//
//
//
//    return 0;
//}