Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

var infty = 1000000000

type DirectedGraphNodeID int

type DirectedGraphNode struct {
	key         DirectedGraphNodeID
	adjacents   []*DirectedGraphNode
	costs       []int
	distance    int
	predecessor *DirectedGraphNode
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]*DirectedGraphNode, nNodes)
	for i := 0; i < nNodes; i++ {
		node := DirectedGraphNode{}
		node.key = DirectedGraphNodeID(i)
		node.distance = infty
		graph.nodes[i] = &node
	}
	return &graph
}

type DirectedGraph struct {
	nodes []*DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(i, j DirectedGraphNodeID, cost int) {
	g.nodes[i].adjacents = append(g.nodes[i].adjacents, g.nodes[j])
	g.nodes[i].costs = append(g.nodes[i].costs, cost)
}

func (g *DirectedGraph) print() {
	for i := 0; i < len(g.nodes); i++ {
		node := g.nodes[i]
		key := node.key
		strings := []string{strconv.Itoa(int(key)), strconv.Itoa(node.distance)}
		for j := 0; j < len(node.adjacents); j++ {
			nodeJ := fmt.Sprintf("(%v, %v)", node.adjacents[j].key, node.costs[j])
			strings = append(strings, nodeJ)
		}
		fmt.Printf("%v\n", strings)
	}
}

func (g *DirectedGraph) relaxEdge(l, r *DirectedGraphNode, w int) {
	if r.distance > l.distance+w {
		// fmt.Printf("%v -> %v, %v\n", l.key, r.key, l.distance+w)
		r.distance = l.distance + w
		r.predecessor = l
	}
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	graph := newDirectedGraph(nNodes)

	for i := 0; i < nNodes; i++ {
		iNode := DirectedGraphNodeID(nextInt())
		nAdjacent := nextInt()
		for j := 0; j < nAdjacent; j++ {
			jNode := DirectedGraphNodeID(nextInt())
			cost := nextInt()
			graph.setAdjacency(iNode, jNode, cost)
		}
	}

	graph.nodes[0].distance = 0
	for iNode := 0; iNode < nNodes; iNode++ {
		for iLeft := 0; iLeft < len(graph.nodes); iLeft++ {
			nodeLeft := graph.nodes[iLeft]
			for iRight := 0; iRight < len(nodeLeft.adjacents); iRight++ {
				nodeRight := nodeLeft.adjacents[iRight]
				cost := nodeLeft.costs[iRight]
				graph.relaxEdge(nodeLeft, nodeRight, cost)
			}
		}
	}

	// graph.print()

	for iNode := 0; iNode < len(graph.nodes); iNode++ {
		node := graph.nodes[iNode]
		fmt.Println(node.key, node.distance)
	}
}

C++: /*
　　　  ∧＿∧　やあ
　　 （´・ω・｀)　　　　　/　　　　　ようこそ、バーボンハウスへ。
　　 ／∇y:::::＼　　　 [￣]　　　　　このテキーラはサービスだから、まず飲んで落ち着いて欲しい。
　　 |:⊃:|:::::|　　　|──|
￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣|　うん、「また」なんだ。済まない。
￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣|￣　  仏の顔もって言うしね、謝って許してもらおうとも思っていない。
￣￣￣￣￣￣￣￣￣￣￣￣￣￣／|
　　　　∇　∇　∇　∇　　　／.／|　　　でも、この提出を見たとき、君は、きっと言葉では言い表せない
　　　　┴　┴　┴　┴　／ ／　  |　　　「ときめき」みたいなものを感じてくれたと思う。
￣￣￣￣￣￣￣￣￣￣|／　　  |　　　殺伐としたコンテストの中で、そういう気持ちを忘れないで欲しい
￣￣￣￣￣￣￣￣￣￣　　　　 |　　　そう思って、この提出を投げたんだ。
　　　(⊆⊇)　(⊆⊇)　(⊆⊇)　　|
　    ||　　 ||　　||　　|　　　 じゃあ、判定を聞こうか。
　　.／|＼　／|＼ ／|＼
*/

#include <iostream>
#include <cstdlib>
#include <algorithm>
#include <array>
#include <bitset>
#include <climits>
#include <cmath>
#include <cstdio>
#include <functional>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <string>
#include <vector>
using namespace std;
#define fst first
#define snd second
#define mp make_pair
#define ALL(obj) (obj).begin(),(obj).end()
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i = (b-1);i>=a;i--)
#define REP(i,n)  FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n) 
#define SIZE(x) ((int)(x).size())
#define debug(x) cerr << #x << " -> " << x << " (line:" << __LINE__ << ")" << '\n';
#define debugpair(x, y) cerr << "(" << #x << ", " << #y << ") -> (" << x << ", " << y << ") (line:" << __LINE__ << ")" << '\n';
typedef long long lint;
typedef pair<int, int> pint;
typedef pair<lint, lint> plint;
typedef vector<lint> vec;
typedef vector<vector<lint>> matrix;
typedef priority_queue<lint> p_que;
typedef priority_queue<lint, vector<lint>, greater<lint>> p_que_rev;
const lint INF = INT_MAX;
const lint LINF = LLONG_MAX;
const lint MOD = 1000000000 + 7;
const double EPS = 1e-9;
const double PI = acos(-1);
const int di[]{0, -1, 0, 1, -1, -1, 1, 1};
const int dj[]{1, 0, -1, 0, 1, -1, -1, 1};

// Graph Templates
using Weight = lint;
// using Flow = int;
struct Edge {
    int src, dst;
    Weight weight;
    // Flow cap;
    Edge() : src(0), dst(0), weight(0) {}
    Edge(int s, int d, Weight w) : src(s), dst(d), weight(w) {}
};
using Edges = vector<Edge>;
using Graph = vector<Edges>;
using Array = vector<Weight>;
using Matrix = vector<Array>;
// const Weight INF = numeric_limits<Weight>::max() / 8;

// add edge a <--(weight = w)--> b
void add_edge(Graph &g, int a, int b, Weight w) {
    g[a].push_back(Edge(a, b, w));
    g[b].push_back(Edge(b, a, w));
}

// add edge a --(weight = w)--> b
void add_arc(Graph &g, int a, int b, Weight w) { g[a].push_back(Edge(a, b, w)); }

// Dijkstra
// g is graph, s is start
vector<Weight> dijkstra(const Graph &g, int s) {
    // const Weight INF = numeric_limits<Weight>::max() / 8;
    using state = tuple<Weight, int>;
    priority_queue<state> q;
    vector<Weight> dist(g.size(), LINF);
    dist[s] = 0;
    q.emplace(0, s);
    while (q.size()) {
        Weight d;
        int v;
        tie(d, v) = q.top();
        q.pop();
        d *= -1;
        /* if(v == t) return d; */
        if (dist[v] < d) continue;
        for (auto &e : g[v]) {
            if (dist[e.dst] > dist[v] + e.weight) {
                dist[e.dst] = dist[v] + e.weight;
                q.emplace(-dist[e.dst], e.dst);
            }
        }
    }
    return dist;
}

int main(){
    int n;
    cin >> n;
    int u, k, v;
    Weight c;
    Graph g;
    vector<Weight> dist;
    g.resize(n);
    for (int i=0; i<n; ++i){
        cin >> u >> k;
        for (int j=0; j<k; ++j){
            cin >> v >> c;
            add_arc(g, u, v, c);
        }
        // add_edge(g, s, t, d);
    }
    dist = dijkstra(g, 0);
    for (int i=0; i<(int)dist.size(); ++i){
        cout << i << " ";
        if(dist[i] != INF){
            cout << dist[i] << endl;
        }
        else {
            cout << "INF" << endl;
        }
    }
    
    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
const int maxn = 111;
int mp[maxn][maxn];
#define INF 0x3f3f3f3f;
int main()
{
	int n;
	cin >> n;
	for (int i = 0;i < n;i++) {
		for (int j = 0;j < n;j++) {
			if (i == j)mp[i][j] = 0;
			else
				mp[i][j] = INF;
		}
	}
	for (int i = 0;i < n;i++)
	{
		int a, k, b, w;
		cin >> a >> k;
		for (int j = 0;j < k;j++)
		{
			cin >> b >> w;
			if(mp[a][b]>w)
			mp[a][b] = mp[b][a] = w;
		}
	}
	for (int k = 0;k < n;k++)
	{
		for (int i = 0;i < n;i++)
		{
			for (int j = 0;j < n;j++)
			{
				if (mp[i][k] + mp[k][j] < mp[i][j])
				{
					mp[i][j] = mp[i][k] + mp[k][j];
				}
			}
		}
	}
	for (int i = 0;i < n;i++)
	{
		cout<<i <<" "<< mp[0][i] << endl;
	}
	return 0;
}