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++: #include<bits/stdc++.h>

using namespace std;
int d[10002];
struct Edge{
    int from,to,w;
};
const int inf=1<<30;
vector<Edge> E;
vector<int> G[10002];
struct node{
    int to,w;
    friend bool operator < (const node& a, const node& b){
        return a.w>b.w;
    }
};
bool vis[10002];
int V;
void dijkstar(int start=0){
    priority_queue<node> que;
    que.push(node {start,0});
    d[start]=0;
    while(!que.empty()){
        node s=que.top();
        que.pop();
        int nowV=s.to,w=s.w;
        if(vis[nowV]) continue;
        vis[nowV]=true;
        for(int i=0;i<G[nowV].size();i++){
            Edge ee=E[G[nowV][i]];
            if(d[ee.to]>d[nowV]+ee.w){
                d[ee.to]=d[nowV]+ee.w;
                que.push(node {ee.to,d[ee.to]});
            }
        }
    }
}

int main(){
    cin>>V;
    for(int i=0;i<V;i++){
        int id,k;
        cin>>id>>k;
        vis[i]=false;
        d[i]=inf;
        while(k--){
            int out,val;
            cin>>out>>val;
            E.push_back(Edge{id,out,val});
            G[id].push_back(E.size()-1);
        }
    }
    dijkstar();
    for(int i=0;i<V;i++){
        cout<<i<<" "<<d[i]<<endl;
    }
}

C++: #include<iostream>
#include<cstdio>
#include<climits>
#include<cstring>
#include<algorithm>
#define INF 1<<25
using namespace std;
typedef long ull;
 
int main(){
  int n;
  int A[1000][1000];
  ull D[1000][1000];
  scanf("%d",&n);
  int u,k,C,V;
  
  for(int i=0;i<=n;i++){
    for(int j=0;j<=n;j++)D[i][j] = INF;
  }
  
  for(int i=0;i<n;i++){
    scanf("%d %d",&u,&k);    
    for(int j=0;j<k;j++){
      scanf("%d %d",&V,&C);
      D[u][V] = C;
      D[V][u] = C;
    }    
  }
  
  for(int i=0;i<n;i++)D[i][i] = 0;
  for(int k=0;k<n;k++)for(int i=0;i<n;i++)for(int j=0;j<n;j++)D[i][j] = min(D[i][j],D[i][k] + D[k][j]);
  for(int i=0;i<n;i++){
    cout << i << " " << D[0][i] << endl;
  }
  
  return 0;
}

C++: #include<iostream>
#include<algorithm>
#define inf 10000000
#define W 0
#define G 1
#define B 2
using namespace std;
int n,color[100];
int g[100][100],d[100],p[100];

void dikstr(int st){
int u,i,j;
	for(i=0;i<n;i++){
	color[i]=W;d[i]=inf;
	}
	d[st]=0;
	p[st]=-1;
	while(true){
	int mincost=inf;
		for(i=0;i<n;i++){
			if(color[i]!=B && d[i]<mincost){
			mincost=d[i];
				u=i;
			}
			
		}
		if(mincost==inf)
		break;
		color[u]=B;
		for(int v=0;v<n;v++){
			if(color[v]!=B && g[u][v]!=inf){
				if(d[u]+g[u][v]<d[v]){
				d[v]=d[u]+g[u][v];
					p[v]=u;
					color[v]=G;
				}
			}
		}
	}
}
main(){
	int i,j,u,k,c,v;
	cin>>n;
	for(i=0;i<n;i++){
		for(j=0;j<n;j++)
		g[i][j]=inf;
	}
	for(i=0;i<n;i++){
	cin>>u>>k;
		for(j=0;j<k;j++){
		cin>>v>>c;
			g[u][v]=c;
		}
	}
	dikstr(0);
	
	for(i=0;i<n;i++)
	cout<<i<<" "<<d[i]<<endl;
	return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
const int INF=1000000000;
int G[100][100];
int d[100],used[100];
int n;
void dijkstra(int s){
    fill(d,d+n,INF);
    fill(used,used+n,false);
    
    d[s]=0;
    while(true){
	int v=-1;
	for(int u=0;u<n;u++){
	    if(used[u]) continue;
	    if(v==-1||d[u]<d[v]) v=u;
	}
	if(v==-1) break;
	used[v]=true;

	for(int u=0;u<n;u++){
	    d[u]=min(d[u],d[v]+G[v][u]);
	}
    }
}
int main(){
    cin>>n;
    fill(G[0],G[n],INF);
    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[u][v]=G[v][u]=c;
	}
    }
    dijkstra(0);
    for(int i=0;i<n;i++){
	cout<<i<<" "<<d[i]<<endl;
    }

    return 0;
}

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 dik(){
int min;
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){
min=INFTY;
int u=-1;
for(int i=0;i<n;i++){
if(min>d[i]&&color[i]!=BLACK){
u=i;
min=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;
}
}

dik();

return 0;
}

C++: #include <stdio.h>
#include <queue>
using namespace std;
struct side{
    int to;
    int cost;
};
struct walk{
    int now;
    int cost;
};
int main(){
    int n,l,m,d[100];
    queue<walk> q;
    vector<side> map[100];
    walk temp,t;
    side s;
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        scanf("%d%d",&l,&m);
        d[i]=-1;
        for(int j=0;j<m;j++){
            scanf("%d%d",&s.to,&s.cost);
            map[l].push_back(s);
        }
    }
    temp.now=temp.cost=0;
    q.push(temp);
    while(!q.empty()){
        temp=q.front();
        q.pop();
        if(d[temp.now]!=-1&&d[temp.now]<=temp.cost)continue;
        d[temp.now]=temp.cost;
        for(int i=0;i<map[temp.now].size();i++){
            t.cost=temp.cost+map[temp.now][i].cost;
            t.now=map[temp.now][i].to;
            q.push(t);
        }
    }
    for(int i=0;i<n;i++){
        printf("%d %d\n",i,d[i]);
    }
}

C++: #include <bits/stdc++.h>

using namespace std;

struct edge {
  int to, weight;
};

void dijkstra(vector<vector<edge>> graph, int start) {
  int n = graph.size();

  int dist[n];
  for (int i = 0; i < n; i++) {
    dist[i] = INT_MAX;
  }
  dist[start] = 0;

  priority_queue<pair<int, int>> que;
  que.push(make_pair(dist[start], start));
  while (!que.empty()) {
    int v = que.top().second;
    int c = que.top().first;
    que.pop();
    for (int i = 0; i < graph[v].size(); i++) {
      edge e = graph[v][i];
      if (dist[e.to] > c + e.weight) {
        dist[e.to] = c + e.weight;
        que.push(make_pair(dist[e.to], e.to));
      }
    }
  }

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

int main() {
  int n;
  cin >> n;
  vector<vector<edge>> graph;
  graph.resize(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;
      graph[u].emplace_back(edge{v, c});
    }
  }

  dijkstra(graph, 0);
}