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 <bits/stdc++.h>
// using namespace std;
// #define rep(i, n) for (int i = 0; i < n; i++)

// int n;
// vector<vector<int>> a(100,vector<int>(100, -1)); // 各頂点間の重みを表す隣接行列
// vector<int> d(100, -1);

// void dijkstra(int start) {
//     vector<int> s;
    
//     s.push_back(start);
//     d[start] = 0;
//     while (s.size() < n) {
//         int min_v = 10000001, min_i;
//         rep(i, s.size()) {
//             int cur = s[i];
//             rep(j, n) {
//                 int adj = a[cur][j];
//                 if (adj != -1 && d[j] == -1 && d[cur] + adj < min_v) {
//                     min_v = d[cur] + adj;
//                     min_i = j;
//                 }
//             }
//         }
//         s.push_back(min_i);
//         d[min_i] = min_v;
//     }
// }

// int main() {
//     scanf("%d", &n);
//     rep(i, n) {
//         int u, k;
//         scanf("%d %d", &u, &k);
//         rep(j, k) {
//             int v, c;
//             scanf("%d %d", &v, &c);
//             a[u][v] = c;
//         }
//     }
//     dijkstra(0);
//     rep(i, n) {
//         printf("%d %d\n", i, d[i]);
//     }
// }

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < n; i++)

const int INF = 1000000000;
int n;
vector<vector<pair<int,int>>> e;
vector<int> d;
vector<bool> t;
void dijkstra(int start) {
    d[start] = 0;
    priority_queue<pair<int,int>, vector<pair<int,int>>, greater<pair<int,int>>> pq;
    pq.push({d[start],start});
    while (not pq.empty()) {
        int u = pq.top().second; // uは最短経路木に含まれない頂点のうちd[u]が最小であるもの
        pq.pop();
        t[u] = true; // uを最短経路木に含ませる
        rep(j, e[u].size()) {
            int v = e[u][j].first; // uの隣接点
            if (t[v] == false) { // 隣接点のうち最短経路木に含まれないもの
                if (d[u] + e[u][j].second < d[v]) { // e[u][j].secondはuから隣接点までの距離
                    d[v] = d[u] + e[u][j].second;
                    pq.push({d[v],v});
                }
            }
        }
    }
}

int main() {
    cin >> n;
    e.resize(n);
    rep(i, n) {
        int u, k;
        cin >> u >> k;
        rep(j, k) {
            int v, c;
            cin >> v >> c;
            e[u].push_back({v,c});
        }
    }
    d.resize(n,INF);
    t.resize(n,false);
    dijkstra(0);
    rep(i, n) {
        printf("%d %d\n", i, d[i]);
    }
}

C++: #include <iostream>
#include <algorithm>
using namespace std;

const int INF = 1 << 29;

int main()
{
    int n,u,k,v,c;
    int V[101][101];
    fill((int*)V, (int*)(V + 101), INF);
    
    cin >> n;
    for(int i = 0; i < n; ++i){
        V[i][i] = 0;
    }
    
    for(int i = 0; i < n; ++i){
        cin >> u >> k;
        for(int j = 0; j < k; ++j){
            cin >> v >> c;
            V[u][v] = c;
        }
    }
    
    for(int k = 0; k < n; ++k){
        for(int i = 0; i < n; ++i){
            for(int j = 0; j < n; ++j){
                V[i][j] = min(V[i][j],V[i][k] + V[k][j]);
            }
        }
    }
    
    for(int i = 0; i < n; ++i){
        cout << i << ' ' << V[0][i] << endl;
    }
    
}

C++: #include <iostream>
using namespace std;

static const int MAX = 100;
static const int INFTY = (1<<21);
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;

int n,M[MAX][MAX];

void dijkstra(){
    int minv;
    int d[MAX],color[MAX];
    
    for(int i=0; i<n; i++){
        d[i] = INFTY;
        color[i] = WHITE;
    }
    
    d[0] = 0;
    color[0] = GRAY;
    while (1) {
        minv = INFTY;
        int u = -1;
        for(int i=0; i<n; i++){
            if(minv > d[i] && color[i] != BLACK){
                u = i;
                minv = d[i];
            }
        }
        if(u==-1) break;
        color[u] = BLACK;
        for(int v=0; v<n; v++){
            if(color[v]!=BLACK && M[u][v]!=INFTY){
                if(d[v] > d[u] + M[u][v]){
                    d[v] = d[u]+M[u][v];
                    color[v] = GRAY;
                }
            }
        }
    }
    for(int i=0; i<n; i++){
        cout << i << " " << (d[i]==INFTY ? -1 : d[i]) << endl;
    }
}

int main(){
    cin >> n;
    for(int i=0; i<n; i++){
        for(int j=0; j<n; j++){
            M[i][j] = INFTY;
        }
    }
    
    int k,c,u,v;
    for(int i=0; i<n; i++){
        cin >> u >> k;
        for(int j=0; j<k; j++){
            cin >> v >> c;
            M[u][v] = c;
        }
    }
    
    dijkstra();
}