Go: package main

import (
	"strconv"
	"fmt"
	"bufio"
	"os"
)
const INF = 1 << 21
var scanner = bufio.NewScanner(os.Stdin)

func nextInt() int {
	scanner.Scan()
	i, e := strconv.Atoi(scanner.Text())
	if e != nil {
		panic(e)
	}
	return i
}


func main() {
	scanner.Split(bufio.ScanWords)
	n := nextInt()
	adj := make([][]int, n)
	for i := range adj {
		adj[i] = make([]int, n)
	}

	for i := 0;i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			v := nextInt()
			c := nextInt()
			adj[u][v] = c
		}
	}

	// for i := range adj {
	// 	fmt.Println(adj[i])
	// }

	dist := make([]int, n)
	prev := make([]int, n)
	visited := make([]bool, n)
	dijkstra := func(start int, size int) {
		for i := 0; i < size; i++ {
			dist[i] = INF
			prev[i] = -1
			visited[i] = false
		}
		dist[start] = 0
		for {
			u := -1
			tmp_min := INF
			for i := 0; i < size; i++ {
				if visited[i] == false && dist[i] < tmp_min {
					tmp_min = dist[i]
					u = i
				}
			}
			if u == -1 {
				break
			}
			visited[u] = true
			for i := 0; i < size; i++ {
				if adj[u][i] > 0 {
					w := adj[u][i]
					newlen := dist[u] + w
					if newlen < dist[i] {
						dist[i] = newlen
						prev[i] = u
					}
				}
			}
		}
	}
	dijkstra(0, n)
	for i, cost := range dist {
		fmt.Printf("%d %d\n", i, cost)
	}
}

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] = INFTY;
  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 < n ; j++){
      cin >> v >> c;
      M[u][v] = c;
    }
  }

  dijkstra();

  return 0;
}

C++: #include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = (a), i##_max = (b); i < i##_max; ++i)
#define RFOR(i, a, b) for (int i = (b)-1, i##_min = (a); i >= i##_min; --i)
#define REP(i, n) for (int i = 0, i##_len = (n); i < i##_len; ++i)
#define RREP(i, n) for (int i = (n)-1; i >= 0; --i)
#define ALL(obj) (obj).begin(), (obj).end()

using namespace std;
using vi = vector<int>;
using vd = vector<double>;
using i64 = int64_t;

constexpr int INF = 1 << 30;
constexpr int MOD = 1000000007;

template <typename T>
void print(vector<T> &v) {
  REP(i, v.size()) {
    if (i) cout << " ";
    cout << v[i];
  }
  cout << endl;
}

void dijkstra(vector<vi> &M) {
  auto n = M.size();
  vi d(n, INF);
  vector<bool> visited(n, false);
  d[0] = 0;
  while (true) {
    auto minv = INF;
    auto u = -1;
    REP(i, n) {
      if (!visited[i] && d[i] < minv) {
        minv = d[i];
        u = i;
      }
    }
    if (u == -1) break;
    visited[u] = true;
    REP(i, n) {
      if (!visited[i]) {
        d[i] = min(d[i], d[u] + M[u][i]);
      }
    }
  }
  REP(i, n) cout << i << " " << (d[i] == INF ? -1 : d[i]) << endl;
}

int main() {
  int n;
  cin >> n;
  vector<vi> M(n, vi(n, INF));
  int k, c, u, v;
  REP(i, n) {
    cin >> u >> k;
    REP(j, k) {
      cin >> v >> c;
      M[u][v] = c;
    }
  }
  dijkstra(M);
}

C++: #include<cstdio>
#include<vector>
#include<algorithm>
#include<utility>
#include<numeric>
#include<iostream>
#include<array>
#include<string>
#include<sstream>
#include<stack>
#include<queue>
#include<list>
#include<functional>
#define _USE_MATH_DEFINES

#include<math.h>
#include<map>

#define SENTINEL 1000000001

#define min(a,b) (a)>(b)?(b):(a)
#define max(a,b) (a)>(b)?(a):(b)

using namespace std;

struct OwnNode
{
	vector<int> to;
	vector<int> to_cost;

	int id;
	bool checked;
	int cost;

	OwnNode(int id):id(id),checked(false),cost(-1){}

	bool operator<(const OwnNode& node)const
	{
		return cost < node.cost;
	}

	bool operator>(const OwnNode& node)const
	{
		return cost > node.cost;
	}

	OwnNode operator-(const OwnNode& node)const
	{
		return cost - node.cost;
	}
};

int main()
{
	int n;
	cin >> n;

	vector<OwnNode> nodes;

	for (int i = 0; i < n; i++)
	{
		int id, k;
		cin >> id >> k;

		nodes.push_back(OwnNode(id));

		for (int j = 0; j < k; j++)
		{
			int v, c;
			cin >> v >> c;
			nodes[i].to.push_back(v);
			nodes[i].to_cost.push_back(c);
		}
	}

	priority_queue<OwnNode, vector<OwnNode>, greater<OwnNode>> pq;

	nodes[0].cost = 0;
	pq.push(nodes[0]);

	while (pq.size() != 0)
	{
		OwnNode tn = pq.top();
		pq.pop();

		nodes[tn.id].checked = true;

		for (int i = 0; i != tn.to.size(); i++)
		{
			if (nodes[tn.to[i]].checked)continue;
			if (nodes[tn.to[i]].cost == -1)
			{
				nodes[tn.to[i]].cost = tn.to_cost[i];
			}
			else
			{
				nodes[tn.to[i]].cost = min(nodes[tn.to[i]].cost, tn.to_cost[i] + tn.cost);
			}
			pq.push(nodes[tn.to[i]]);
		}
	}

	for (auto& node : nodes)
	{
		printf("%d %d\n", node.id, node.cost);
	}

	return 0;
}