Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)

	g := makeGraph(n)
	for i := 0; i < n; i++ {
		u := getNextInt(scanner)
		k := getNextInt(scanner)
		for ii := 0; ii < k; ii++ {
			v := getNextInt(scanner)
			c := getNextInt(scanner)
			g[u][v] = c
		}
	}

	ans := make([]int, n)
	im := make(IntMap, 1)
	im.increment(0)
	for len(im) < n {
		min := 1 << 30
		x := -1
		for u := range im {
			for v := 0; v < n; v++ {
				if im.get(v) != 0 {
					continue
				}
				if min > ans[u]+g[u][v] {
					min = ans[u] + g[u][v]
					x = v
				}
			}
		}
		im.increment(x)
		ans[x] = min
	}

	for i := 0; i < n; i++ {
		fmt.Fprintln(writer, fmt.Sprintf("%d %d", i, ans[i]))
	}
	writer.Flush()
}

func makeGraph(n int) [][]int {
	g := make([][]int, n)
	for i := 0; i < n; i++ {
		g[i] = make([]int, n)
		for ii := 0; ii < n; ii++ {
			g[i][ii] = 1 << 30
		}
	}

	return g
}

// IntMap ...
type IntMap map[int]int

func (m IntMap) get(key int) int {
	if _, ok := m[key]; ok {
		return m[key]
	}
	return 0
}
func (m IntMap) increment(key int) {
	if _, ok := m[key]; ok == false {
		m[key] = 0
	}
	m[key]++
}

C++: #ifdef LOCAL_BUILD
#include "pch.h"
#define DLOG(msg) cout << "#" << __LINE__ << ":" << msg << endl;
#define DLOG_V(var) \
  cout << "#" << __LINE__ << ":" << #var << " : " << var << endl;
#else
#include <bits/stdc++.h>
#define DLOG(msg)
#define DLOG_V(var)
#endif
using namespace std;

int main() {
  int n;
  cin >> n;
  vector<vector<pair<int, int>>> edges(n, vector<pair<int, int>>());
  for (int i = 0; i < n; ++i) {
    int u, k;
    cin >> u >> k;
    for (int j = 0; j < k; ++j) {
      int v, c;
      cin >> v >> c;
      edges[i].push_back(make_pair(v, c));
    }
  }
  int count = 1;
  constexpr auto not_yet = numeric_limits<int>::max();
  vector<int> costs(n, not_yet);
  costs[0] = 0;
  auto cmp = [](const pair<int, int>& lhs, const pair<int, int>& rhs) {
    return lhs.second > rhs.second;
  };
  priority_queue<pair<int, int>, vector<pair<int, int>>, decltype(cmp)> q(cmp);
  for (auto&& edge : edges[0]) {
    q.push(edge);
  }
  int cost = 0;
  while (true) {
    auto edge = q.top();
    q.pop();
    if (costs[edge.first] > cost + edge.second) {
      cost += edge.second;
      assert(costs[edge.first] == not_yet);
      for (auto&& e : edges[edge.first]) {
        q.push(e);
      }
      costs[edge.first] = cost;
      if (++count == n) {
        break;
      }
    }
  }
  for (int i = 0; i < n; ++i) {
    cout << i << " " << costs[i] << endl;
  }
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;

struct Edge{
    ll target;
    ll weight;
};

struct State{
    ll node;
    ll sum_of_weight;

    bool operator < (const State& s)  const {
        return sum_of_weight > s.sum_of_weight;
    }
};

typedef vector<vector<Edge> > graph;

void dijkstra(graph &g, vector<ll>&d, ll start){

    priority_queue<State> pq;
    pq.push(State{start,0});

    while( pq.size() ){

        State s = pq.top(); pq.pop();

        if( d[s.node] != -1 ) continue;
        d[s.node] = s.sum_of_weight;

        for(auto edge: g[s.node]) {
            if( d[edge.target] != -1 ) continue;
            pq.push(State{edge.target, s.sum_of_weight + edge.weight});

        }
    }

}


int main(){

    ll N;
    cin >> N;

    graph G(N);
    for (int i = 0; i < N; i++)
    {
        ll u,k;
        cin >> u >> k;
        for (int j = 0; j < k; j++)
        {
            ll v,c;
            cin >> v >> c;
            G[u].push_back(Edge{v,c});
        }
    }

    vector<ll> d(N,-1);

    ll count = 1;
    dijkstra(G,d,0);

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

C++: #include<iostream>
#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
int main() {
	int n, u, k, v, c, i, j, d[100][100], m[100][100], o, p[100] = { 0 }, e, q = 0;
	memset(m, 0x7f, sizeof(m));
	memset(d, 0x7f, sizeof(d));
	d[0][0] = 0;
	cin >> n;
	for (i = 0; i < n; i++) {
		cin >> u >> k;
		for (j = 0; j < k; j++) {
			cin >> v >> c;
			m[u][v] = c;
		}
	}
	p[0] = 1;
	for (i = 1; i < n; i++) {
		o = d[0][n - 1];
		for (j = 0; j < n; j++) {
			d[i][j] = min(d[i][j], m[q][j] + d[i - 1][q]);
			d[i][j] = min(d[i][j], d[i - 1][j]);
			if (o >= d[i][j] && p[j] == 0) {
				e = j;
				o = d[i][j];
			}
		}
		p[e] = 1;
		q = e;
	}
	for (i = 0; i < n; i++)cout << i << ' ' << d[n - 1][i] << endl;
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
struct node{
	int v,c;
	bool operator<(const node&p)const{
		return c>p.c;
	}
};
int d[100005];
vector<node> e[100005];
bool ok[100005];
int n;
void solve(){
	priority_queue<node> q;
	ok[0]=1;
	for(int i=0;i<e[0].size();i++)q.push(e[0][i]);
	int k=1;
	while(k!=n){
		node v=q.top();q.pop();
		if(ok[v.v])continue;
		d[v.v]=v.c;
		ok[v.v]=1;
		k++;
		for(int j=0;j<e[v.v].size();j++)
			q.push({e[v.v][j].v,e[v.v][j].c+v.c});
	}
	for(int i=0;i<n;i++)
		cout<<i<<' '<<d[i]<<"\n";
}
int main(){
//	freopen("a.txt","r",stdin);
	cin.tie(0);
	int u,v,k,c;
	cin>>n;
	while(cin>>u>>k){
		for(int i=0;i<k;i++){
			cin>>v>>c;
			e[u].push_back({v,c});
		}
	}
	solve();
	return 0;
}