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<stdio.h>
#define MAX 2001
#define NIL -1
#define B -2
#define W -1
#define G 0
#include<queue>
#include<vector>
#include<algorithm>
using namespace std;

int d[MAX];
int p[MAX];
int color[MAX];
int n;
int u;
int k;
int c;
int v;
int M[MAX][MAX];
queue <int> Q;

void DIJKSTRA() {
	for (int i = 0; i < n; i++) {
	    d[i] = 9000000;
		p[i] = NIL;
		color[i] = W;
	}
	d[0] = 0;
	color[0] = B;
	int s = 0;
	Q.pop();
	int count = 0;
	while (!Q.empty()) {
		count++;
		for (int i = 0; i < n; i++) {
			if (M[s][i] != -1 && color[i] != B) {
				
				if (d[i] > d[s] + M[s][i]) {
					
					d[i] = d[s] + M[s][i];
					p[i] = s;
					color[i] = G;
					
					
				}
			}
		}
		int a = 0;
		int mini = MAX;
		for (int j = 0; j < n; j++) {
			
			if (color[j] == G) {
		
				if(mini>d[j]){
					a = j;
				}
				mini = min(mini, d[j]);
			}

		}
		s = a;
		color[a] = B;
		Q.pop();
		
	}
	
}
int main(){

	cin >> n;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			M[i][j] = -1;
		}
	}

	for (int i = 0; i < n; i++) {
		cin >> u; cin >> k;
		for (int j = 0; j < k; j++) {
			cin >> v >> c;
			M[u][v] = c;
			Q.push(i);
		}
	}

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

C++: #include <cstdio>

const int N = 100;
const int INF = 10000001;
int cost[N][N];
int minCost[N] = {0};
bool isDecide[N] = {false};

int getMinIndex(int n) {
        int minIndex = -1;
        int cost = INF;
        for (int i = 0; i < n; i++) {
                if (minCost[i] < cost && !isDecide[i]) {
                        cost = minCost[i];
                        minIndex = i;
                }
        }

        return minIndex;
}

int main() {
        for (int i = 0; i < N; i++) {
                for (int j = 0; j < N; j++) {
                        cost[i][j] = -1;
                }
        }
        for (int i = 1; i < N; i++) {
                minCost[i] = INF;
        }
        int n, u, k, v, c;

        scanf("%d", &n);
        for (int i = 0; i < n; i++) {
                scanf("%d %d", &u, &k);
                for (int j = 0; j < k; j++) {
                        scanf("%d %d", &v, &c);
                        cost[u][v] = c;
                }
        }
        while (true) {
                int from = getMinIndex(n);
                if (from < 0) {
                        break;
                }
                isDecide[from] = true;
                for (int to = 0; to < n; to++) {
                        if (cost[from][to] < 0 || isDecide[to]) {
                                continue;
                        }
                        int newCost = minCost[from] + cost[from][to];
                        if (newCost < minCost[to]) {
                                minCost[to] = newCost;
                        }
                }
        }
        for (int i = 0; i < n; i++) {
                printf("%d %d\n", i, minCost[i]);
        }

        return 0;
}

C++: #include <bits/stdc++.h>
#define REP(i, a, b) for(int i = (a); i < (b); i++)
#define RREP(i, a, b) for(int i = (a); i >= (b); i--)
#define pq priority_queue
#define P pair<int, int>
#define P2 pair<int, P>
#define P3 pair<int, P2>
typedef long long ll; typedef long double ld;
using namespace std;
const int INF = 1e9, MOD = 1e9+7, around[] = {0, 1, 1, -1, -1, 0, -1, 1, 0, 0};
const int vx[] = {1, 0, -1, 0}, vy[] = {0, 1, 0, -1};
const ld PI = abs(acos(-1));
const int sqrtN = 512;
const int logN = 32;
const ll LINF=1e18;

template<typename T>
struct Dijkstra{
	struct edge{
		int to;
		T cost;
	};
	const T INF;
	vector<vector<edge>> g;
	vector<T> min_cost;
	
	Dijkstra(int n) : INF(numeric_limits<T>::max()){
		g.resize(n);
	}
	
	void add_edge(int from, int to, T cost){
		g[from].push_back(edge{to, cost});
	}
	
	vector<T> dijkstra(int s){
		min_cost.assign(g.size(), INF); min_cost[s] = 0;
		pq<pair<T, int>, vector<pair<T, int>>, greater<pair<T, int>>> qu;
		qu.push({0, s});
		
		while(!qu.empty()){
			auto p = qu.top(); qu.pop();
			
			for(auto e:g[p.second]){
				if(p.first + e.cost >= min_cost[e.to]) continue;
				min_cost[e.to] = p.first + e.cost;
				qu.push({min_cost[e.to], e.to});
			}
		}
		
		return min_cost;
	}
};


int main(){
	int n; cin >> n;
	Dijkstra<ll> dijk(n);
	for(int i = 0; i < n; i++){
		int k; cin >> k >> k;
		
		for(int j = 0; j < k; j++){
			int a, b; cin >> a >> b;
			dijk.add_edge(i, a, (ll)b);
			dijk.add_edge(a, i, (ll)b);
		}
	}
	
	vector<ll> min_cost = dijk.dijkstra(0);
	for(int i = 0; i < n; i++) cout << i << " " << min_cost[i] << endl;
	return 0;
}