Go: package main

import (
	"fmt"
	"bufio"
	"os"
	"strconv"
	"container/heap"
)

type Node struct {
	Id int
	Dis int
}

type PriorityQueue []*Node

func (pq PriorityQueue) Len() int { return len(pq) }

func (pq PriorityQueue) Less(i, j int) bool {
	return pq[i].Dis < pq[j].Dis
}

func (pq PriorityQueue) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
}

func (pq *PriorityQueue) Push(x interface{}) {
	*pq = append(*pq, x.(*Node))
}

func (pq *PriorityQueue) Pop() interface{} {
	n := len(*pq)
	pop := (*pq)[n-1]
	*pq = (*pq)[0:n-1]
	return pop
}

func main() {
	var n int
	fmt.Scan(&n)

	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	g := make([][]int, n)
	c := make([][]int, n)
	pq := make(PriorityQueue, 0, n)
	d := make([]int, n)
	for i := 0; i < n; i++ {
		sc.Scan()
		u, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		k, _ := strconv.Atoi(sc.Text())
		g[u] = make([]int, k)
		c[u] = make([]int, k)
		for j := 0; j < k; j++ {
			sc.Scan()
			g[u][j], _ = strconv.Atoi(sc.Text())
			sc.Scan()
			c[u][j], _ = strconv.Atoi(sc.Text())
		}

		if u == 0 {
			d[u] = 0
		} else {
			d[u] = 1 << 30
		}
		pq.Push(&Node{u, d[u]})
	}
	heap.Init(&pq)

	for pq.Len() > 0 {
		node := heap.Pop(&pq).(*Node)
		for i := 0; i < len(g[node.Id]); i++ {
			nextId := g[node.Id][i]
			nextDis := node.Dis + c[node.Id][i]
			if nextDis < d[nextId] {
				d[nextId] = nextDis
				heap.Push(&pq, &Node{nextId, nextDis})
			}
		}
	}

	wr := bufio.NewWriter(os.Stdout)
	for i := 0; i < n; i++ {
		wr.WriteString(strconv.Itoa(i))
		wr.WriteString(" ")
		wr.WriteString(strconv.Itoa(d[i]))
		wr.WriteString("\n")
	}
	wr.Flush()
}

C++: #include <iostream>
#include <vector>
#include <queue>
using namespace std;
static const int MAX = 10000;
int N;
vector<pair<int, int>> adj[MAX];
int color[MAX];
int d[MAX];
int INF = 1 << 30;

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

void pa() {
    for (int i = 0; i < N; i++) {
        cout << i << " ";
        for (int j = 0; j < adj[i].size(); j++) {
            cout << adj[i][j].second << " ";
        }
        cout << endl;
    }
    cout << endl;
}

void dijkstr() {
    int i,j;
    priority_queue<pair<int, int>> PQ;
    PQ.push(make_pair(0, 0));
    
    d[0] = 0;
    cout << N << endl;
    for (i = 0; i < N; i++) {
        pair<int, int> p = PQ.top(); PQ.pop();
        
        //int c = p.first;
        int id = p.second;
        
        color[id] = 1;
        for (j = 0; j < adj[id].size(); j++) {
            auto node = adj[id][j];
            int c = node.first;
            int k = node.second;
            if (color[k] != 1) {
                if (d[k] > d[id] + c) {
                    d[k] = d[id] + c;
                    PQ.push(make_pair(-c, k));
                }
            }
        }
    }
}



int main(int argc, const char * argv[]) {
    int i,j;
    cin >> N;
//    pd();

    for (i = 0; i < N; i++) {
        int u,k;
        cin >> u >> k;
        color[i] = 0;
        d[i] = INF;
        for (j = 0; j < k; j++) {
            int v, c;
            cin >> v >> c;
            adj[u].push_back(make_pair(c, v));
        }
    }
    
    //pa();
    
    dijkstr();
    
    for (i = 0; i < N; i++) {
        cout << i << " " << d[i] << endl;
    }
    
    
    return 0;
}

C++: #define _USE_MATH_DEFINES

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>

using namespace std;

#define MAX_V 200000

typedef pair<long long int, long long int> P;
long long int INF = 1e18;

struct edge{
	int to;
	long long int cost;
};

vector<edge> G[MAX_V];
long long int d[MAX_V];

// 速さはO(|E|log|V|)

void shortest_path(int s, int V){ // Vは頂点数
	
	priority_queue<P, vector<P>, greater<P> > que;
	
	for(int i = 0; i < V; i++){
		d[i] = INF;
	}
	d[s] = 0;
	
	que.push(P(0, s));
	
	while(!que.empty()){
		
		P p = que.top();
		que.pop();
		
		int v = p.second;
		
		if(d[v] < p.first){
			continue;
		}
		
		for(int i = 0; i < G[v].size(); i++){
			edge e = G[v][i];
			if(d[e.to] > e.cost + d[v]){
				d[e.to] = d[v] + e.cost;
				que.push(P(d[e.to], e.to));
			}
		} // 頂点への最小コストを更新
	}
}

int main(){
	
	int V;
	cin >> V;
	
	for(int i = 0; i < V; i++){
		int u, num;
		cin >> u >> num;
		for(int j = 0; j < num; j++){
			edge e;
			cin >> e.to >> e.cost;
			G[u].push_back(e);
		}
	}
	
	shortest_path(0, V);
	
	for(int i = 0; i < V; i++){
		cout << i << " " << d[i] << endl;
	}
	
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
using UL = unsigned int;
using ULL = unsigned long long;
using LL = long long;
#define rep(i,n) for(UL i=0; i<(n); i++)

template<class E>
using nega_queue=priority_queue<E,vector<E>,greater<E>>;

UL N;
ULL D[100000];
vector<pair<UL,ULL>> E[100000];

int main() {
 scanf("%u",&N);
 rep(i,N){
  UL u,k; scanf("%u%u",&u,&k);
  rep(j,k){
   UL v,c; scanf("%u%u",&v,&c);
   E[u].push_back({v,c});
  }
 }
 rep(i,N) D[i]=~0u;
 nega_queue<pair<ULL,UL>> G;
 G.push({0,0});
 int ans=0;
 while(G.size()){
  ULL d=G.top().first;
  UL p=G.top().second;
  G.pop();
  if(D[p]!=~0u) continue;
  D[p]=d;
  for(auto e:E[p]) G.push({d+e.second,e.first});
 }
 rep(i,N) printf("%u %llu\n",i,D[i]);
 return 0;
}

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

#define MAX 10001
#define INF 5000001

int a[MAX][MAX];
int n;
int d[MAX];

void Relax(int u, int v){
  if(d[v]> d[u]+a[u][v]){
    d[v]=d[u]+a[u][v];
  
  }
}

void ISS(int s){
  int v;
  for(v=0; v<n; v++){
    d[v]=INF;
  }
  d[s]=0;
}

void Dijkstra(int s){
  int i, v1, v, minv, u; 
  int flag[MAX];
  ISS(s);
  
  for(i=0; i<n; i++) flag[i]=0;

  for(v1=0; v1<n; v1++){
    
      minv = INF;
      // decide u
      for ( i = 0; i < n; i++ ){
          if(flag[i]==1) continue; 
          if(d[i]<=minv){
              u=i;
              minv=d[i];
          }
      }   
      for(v=0; v<n; v++){
          if(a[u][v]==-1) continue;
          if(flag[v]==1) continue;
          /* if(a[u][v]<d[v]){
             d[v]=a[u][v];
             }*/
          Relax(u, v);
      }
      flag[u]=1;
  }
}

int main(){

  int i, j ,u ,k,v,c;
  // int a[MAX][MAX];
  cin>>n;

  for(i=0; i<n; i++){
    for(j=0; j<n; j++){
      a[i][j]=-1;
    }
  }

  for(i=0; i<n; i++){
      cin>>u>>k;
    for(j=0; j<k; j++){
        cin>>v>>c;
        a[i][v]=c;
    }
  }

  /*for(i=0; i<n; i++){
    for(j=0; j<n; j++){
    cout<<a[i][j]<<endl;
    }
    cout<<endl;
    }*/
  Dijkstra(0);
  for(i=0; i<n; i++){
      cout<<i<<" "<<d[i]<<endl;
  }

  return 0;
}