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<bits/stdc++.h>
#define INF 1e9
using namespace std;
typedef pair<uint32_t,uint32_t> P;

int bitSearchReverse(uint32_t x){
    if(x==0)return -1;
    return 31-__builtin_clz(x);
}
struct RadixHeap{
    vector<P>v[33];
    uint32_t last,sz;
    RadixHeap(){
        last=sz=0;
    }
    void push(P p){
        assert(last<=p.first);
        sz++;
        v[bitSearchReverse(p.first^last)+1].push_back({p.first,p.second});
    }
    P top(){
        return pop(false);
    }
    P pop(bool f=true){
        assert(sz);
        if(!v[0].size()){
            int i=1;
            while(!v[i].size())++i;
            last=min_element(v[i].begin(),v[i].end())->first;
            for(P p:v[i])v[bitSearchReverse(p.first^last)+1].push_back(p);
            v[i].clear();
        }
        P r=v[0].back();
        if(f){
            sz--;
            v[0].pop_back();
        }
        return r;
    }
    int size(){
        return sz;
    }
    bool empty(){
        return sz==0;
    }
    void clear(){
        last=sz=0;
        for(auto a:v)a.clear();
    }
};
struct Graph{
    Graph(int n):E(n),d(n){}
    vector<vector<P>>E;
    vector<uint32_t>d;
    void add_edge(int a,int b,uint32_t c){
        E[a].emplace_back(b,c);
    }
    void dijkstra(int s){
        RadixHeap H;
        fill(d.begin(),d.end(),INF);
        H.push({d[s]=0,s});
        while(H.size()){
            P e=H.top();H.pop();
            if(e.first>d[e.second])continue;
            for(P& a:E[e.second]){
                uint32_t x=a.first,y=a.second+e.first;
                if(y<d[x])d[x]=y,H.push({y,x});
            }
        }
    }
};

main(){
    int N;
    cin>>N;
    Graph G(N);
    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;
            G.add_edge(u,v,c);
        }
    }
    G.dijkstra(0);
    for(int i=0;i<N;++i)
        cout<<i<<' '<<G.d[i]<<endl;
}

/***************************************

referred
https://github.com/yosupo06/Algorithm/blob/master/datastructure/buf/RadixHeap.h

****************************************/

C++: #include <iostream>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>	// require sort next_permutation count __gcd reverse etc.
#include <cstdlib>	// require abs exit atof atoi 
#include <cstdio>		// require scanf printf
#include <functional>
#include <numeric>	// require accumulate
#include <cmath>		// require fabs
#include <climits>
#include <limits>
#include <cfloat>
#include <iomanip>	// require setw
#include <sstream>	// require stringstream 
#include <cstring>	// require memset
#include <cctype>		// require tolower, toupper
#include <fstream>	// require freopen
#include <ctime>		// require srand
#define rep(i,n) for(int i=0;i<(n);i++)
#define ALL(A) A.begin(), A.end()
#define INF 1<<20

using namespace std;

typedef long long ll;
typedef pair<int, int> P;

const int max_v = 10005;

struct edge{ int to, cost; };
vector<edge> G[max_v];
int d[max_v];

void dijkstra (int n )
{
	priority_queue<P, vector<P>, greater<P> > que;
	fill (d, d+n, INF );
	d[0] = 0;
	que.push (P (0, 0 ) );

	while (!que.empty() ){
		P p = que.top(); que.pop();
		int v = p.second;
		if (d[v] < p.first ) continue;
		rep (i, G[v].size() ){
			edge e = G[v][i];
			if (d[e.to] > d[v] + e.cost ){
				d[e.to] = d[v] + e.cost;
				que.push (P (d[e.to], e.to ) );
			} // end if
		} // end rep
	} // end while
}

int main()
{
	ios_base::sync_with_stdio(0);
	int n; cin >> n;
	rep (i, n ){
		int u, k; cin >> u >> k;
		while (k-- ){
			int v, c; cin >> v >> c;
			edge ne; ne.to = v; ne.cost = c;
			G[u].push_back (ne );
		} // end while
	} // end rep
	dijkstra (n );

	rep (i, n ) cout << i << ' ' << d[i] << endl;
		
	return 0;
}

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

const long long INFF = 1e18;

const int MAX_N = 11000;
using TYPE = long long; // ?????¢???????????\??????
vector<pair<int, TYPE> > G[MAX_N];

vector<TYPE> dijkstra(int start){
	vector<TYPE> dist(MAX_N, INFF);
	dist[start] = 0;//dist[i] :=???start->i?????§??????????????¢
	priority_queue<pair<TYPE, int>, vector<pair<TYPE, int> >, greater<pair<TYPE, int> > >  que;
	que.push(make_pair(0, start));
	while(!que.empty()){
		TYPE cost; int u;//????????§???????????£????????? ?????¨?????????
		cost = que.top().first, u = que.top().second;
		que.pop();
		if(dist[u] < cost) continue;
		for (auto tmp : G[u]){
			int v = tmp.first; TYPE time = tmp.second;//??£??\???????????? ?????????????????§????????????
			if(dist[v] > dist[u] + time){//u->v
				if(dist[v] != INFF) printf("%f %f\n", dist[v], dist[u] + time);
				dist[v] = dist[u] + time;
				que.push(make_pair(dist[v], v));
			}
		}
	}
	return dist;
}


int main(void) {
	int n; cin >> n;
	rep(q, n) {
		int u, k; cin >> u >> k;
		vector<int> v(k), c(k);
		rep(i, k) cin >> v[i] >> c[i];
		rep(i, k) G[u].push_back(make_pair(v[i], c[i])), G[v[i]].push_back(make_pair(u, c[i]));
	}
	auto dist = A_star(0);
	rep(i, n) printf("%d %d\n", i, dist[i]);
	return 0;
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
using namespace std;
static const int INFTY=(1<<21);
#define WHITE 0
#define GRAY 1
#define BLACK 2
#define MAX 10002
int n,M[MAX][MAX],color[MAX],d[MAX];
vector <pair<int,int> > adj[MAX];
void dijkstra(){
    priority_queue <pair<int,int> > PQ;
    d[0]=0;
    color[0]=GRAY;
    PQ.push(make_pair(0,0));
    while(!PQ.empty()){
        pair<int,int> f=PQ.top();
        PQ.pop();
        int u=f.second;
        color[u]=BLACK;
        if(d[u]<f.first*(-1)) continue;

        for(int j=0;j<adj[u].size();j++){
            int v=adj[u][j].first;
            if(color[v]==BLACK) continue;
            if(d[v]>d[u]+adj[u][j].second){
                d[v]=d[u]+adj[u][j].second;
                PQ.push(make_pair(d[v]*(-1),v));
                color[v]=GRAY;
            }
        }
    }
    for(int i=0;i<n;i++){
        cout<<i<<" "<<(d[i]==INFTY ? -1:d[i])<<endl;
    }
}
int main(){
   int u,k,v,c;
   cin>>n;
   for(int i=0;i<n;i++){
       cin>>u>>k;
       for(int j=0;j<k;j++){
           cin>>v>>c;
           adj[u].push_back(make_pair(v,c));
       }
   }
   for(int i=0;i<n;i++){
       color[i]=WHITE;
       d[i]=INFTY;
   }
   dijkstra();
   return 0;
}