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 <stdio.h>
#include <vector>
#include <list>
#include <map>
#include <array>
#include <memory>
#include <string>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <cmath>
#include <unordered_map>
#include <stdexcept>
#include <numeric>
#include <queue>

using std::string;
using std::vector;


//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// util
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

std::vector<std::string> split(const std::string& input, char delimiter)
{
    std::istringstream stream(input);

    std::string field;
    std::vector<std::string> result;
    while (std::getline(stream, field, delimiter)) {
        result.push_back(field);
    }
    return result;
}



//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// user func
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

void printList(const vector<int>& list) {
    // print
    for(int i = 0; i < list.size(); i++){
        printf("%d", list[i]);
        if ( i + 1 != list.size() ) {
            printf(" ");
        }
    }
    printf("\n");
}



//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// logic
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

static int MAX = 1000000;

class Node{
public:
    Node(int id, int numEdge)
     : id(id)
     , edges(vector<int>(numEdge, MAX))
    {
        // constructer
    }
    
    void Edge(int id, int weight){
        this->edges[id] = weight;
    }

    vector<int> Edges() {
        return this->edges;
    }

    int id;
    bool done = false;
    vector<int> edges;
};

class List{
public:
    // constructer
    List(int numNode)
        : results(numNode)
    {
        for (int i = 0; i < numNode; i++) {
            this->nodes.push_back(Node(i, numNode));
            this->results[i] = MAX;
        }
    }

    void SetWeight(int from, int to, int weight)
    {
        this->nodes[from].Edge(to, weight);
    }
    
    vector<int> ShortedPath() {
        // this->Enqueue(0);
        this->results[0] = 0;
        this->queue.push(0);
        this->Traverse();
        return this->results;
    }

    void Traverse() {
        while(!this->queue.empty()) {
            int queueIndex = queue.front();
            queue.pop();
            vector<int> edges = this->nodes[queueIndex].Edges();
            for (int i = 0; i < edges.size(); i++) {
                // update result
                int myWeight = this->results[queueIndex];
                this->results[i] = std::min(this->results[i], myWeight + edges[i]);
            }
            // printList(this->results);
            // enqueue
            this->Enqueue(queueIndex);
            // done flag
            this->nodes[queueIndex].done = true;
        }
    }

    void Enqueue(int index) {
        // copy weights
        if (this->nodes[index].done) return;
        std::list<std::pair<int, int>> weights;
        for (int i = 0; i <  this->nodes[index].Edges().size(); i++) {
            weights.push_back(std::make_pair(i, this->nodes[index].Edges()[i]));
        }
        // sort
        weights.sort([](auto& lhs, auto& rhs){
            return lhs.second < rhs.second;
        });
        // enqueue
        for (auto weight : weights){
            queue.push(weight.first);
        }
    }
    
    

    void Print() {
        for (int i = 0; i < this->nodes.size(); i++) {
            printf("%d: ", i);
            for (int j = 0; j < this->nodes[i].Edges().size(); j++) {
                printf("%d (%d) ", j, this->nodes[i].Edges()[j]);
            }
            printf("\n");
        }
    }
private:
    std::queue<int> queue;
    std::vector<int> results;
    vector<Node> nodes;
};

void solve() {

    int n;
    scanf("%d", &n);
    List list(n);

    for (int i = 0; i < n; i++){
        int key;
        scanf("%d", &key);
        int k;
        scanf("%d", &k);
        for (int j = 0; j < k; j++) {
            int dest;
            int weight;
            scanf("%d %d", &dest, &weight);
            list.SetWeight(key, dest, weight);
        }
    }
    // list.Print();
    auto result = list.ShortedPath();
    for(int i = 0; i < result.size(); i++) {
        printf("%d %d\n", i, result[i]);
    }
}

void test(){

}
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// main
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
int main() {
    solve();
    // test();
    return 0;
}