Go: package main

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

const NIL = -1

type Node struct {
	id     int
	weight int
}

func init() {
	sc.Split(bufio.ScanWords)
}

type NodeHeap []Node

func (h NodeHeap) Len() int           { return len(h) }
func (h NodeHeap) Less(i, j int) bool { return h[i].weight < h[j].weight }
func (h NodeHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }

func (h *NodeHeap) Push(x interface{}) {
	*h = append(*h, x.(Node))
}

func (h *NodeHeap) Pop() interface{} {
	old := *h
	n := len(old)
	x := old[n-1]
	*h = old[0 : n-1]
	return x
}

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

func scanString() string {
	sc.Scan()
	return sc.Text()
}

func init() {
	sc.Split(bufio.ScanWords)
}

func main() {
	n := scanInt()

	list := make([][]int, n)
	weight := make([]int, n)
	for i := range list {
		list[i] = make([]int, n)
		weight[i] = NIL
		for j := range list[i] {
			list[i][j] = NIL
		}
	}

	for i := 0; i < n; i++ {
		u := scanInt()
		k := scanInt()
		for j := 0; j < k; j++ {
			v := scanInt()
			w := scanInt()
			list[u][v] = w
		}
	}

	start := Node{id: 0, weight: 0}
	h := &NodeHeap{start}
	heap.Init(h)

	for h.Len() > 0 {
		node := heap.Pop(h).(Node)
		if weight[node.id] != NIL {
			continue
		}
		weight[node.id] = node.weight

		for i, w := range list[node.id] {
			if w == NIL {
				continue
			}
			heap.Push(h, Node{id: i, weight: w + node.weight})
		}
	}

	w := bufio.NewWriter(os.Stdout)
	for i := 0; i < n; i++ {
		fmt.Fprint(w, i)
		fmt.Fprint(w, " ")
		fmt.Fprint(w, weight[i])
		fmt.Fprintln(w)
	}
	w.Flush()
}

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] = GRAY;
  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 < k; j++)  {
      cin >> v >> c;
      M[u][v] = c;
    }
  }
 
  dijkstra();
  
  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 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]=GRAY;
	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<k;j++){	
			cin>>v>>c;
			M[u][v]=c;
		}
	}
	
	dijkstra();
	
	return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define repr(i, n) for (int i = (n); i >= 0; --i)
#define FOR(i, m, n) for (int i = (m); i < (n); ++i)
#define FORR(i, m, n) for (int i = (m); i >= (n); --i)
using namespace std;
typedef long long ll;
const ll mod = 1000000007;
const ll mod2 = 998244353;

const int MAX = 105;
const int INF = 1000000005;
const int white = 0;
const int gray = 1;
const int black = 2;

int n, M[MAX][MAX], color[MAX], d[MAX];

void dijkstra(int s) {
  rep(i, n) {
    color[i] = white;
    d[i] = INF;
  }
  d[s] = 0;
  color[0] = gray;
  while (1) {
    int u = -1;
    int mincost = INF;
    rep(i, n) {
      if (color[i] != black && d[i] < mincost) {
        mincost = d[i];
        u = i;
      }
    }
    if (mincost == INF) break;
    color[u] = black;
    rep(v, n) {
      if (color[v] != black && M[u][v] != INF) {
        if (d[u] + M[u][v] < d[v]) {
          d[v] = d[u] + M[u][v];
          color[v] = gray;
        }
      }
    }
  }
  rep(i, n) {
    cout << i << " " << (d[i] == INF ? -1 : d[i])<< endl;
  }
}

int main() {
  cin >> n;
  rep(i, n) {
    rep(j, n) {
      M[i][j] = INF;
    }
  }
  int u, k, v, c;
  rep(i, n) {
    cin >> u >> k;
    rep(j, k) {
      cin >> v >> c;
      M[u][v] = c;
    }
  }
  dijkstra(0);

  
  return 0;
}

C++: #include <bits/stdc++.h>
#define INF 1000000000
#define MAX_N 100
using namespace std;
int n;
int d[MAX_N];

struct edge {
	int to, cost;
	edge(int to_, int cost_) : to(to_), cost(cost_) {}
};
typedef pair<int, int> P;
vector<edge> G[MAX_N];

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

	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] > d[v] + e.cost) {
				d[e.to] = d[v] + e.cost;
				que.push(P(d[e.to], e.to));
			}
		}
	}
}

int main()
{
	cin >> n;
	for (int i = 0, u, k; i < n; i++) {
		cin >> u >> k;
		for (int j = 0, v, c; j < k; j++) {
			cin >> v >> c;
			G[u].push_back(edge(v, c));
		}
	}
	Dijkstra(0);
	for (int i = 0; i < n; i++) {
		cout << i << ' ' << d[i] << endl;
	}
	return 0;
}

C++: #include<iostream>
#define MAX 100
#define MAXNUM 10000001
using namespace std;
int n, minv, M[MAX][MAX];
int w[MAX], color[MAX] = {};

void dijkstra() {
	for (int i = 0; i < n; i++) {
		w[i] = MAXNUM;
	}
	w[0] = 0;
	color[0] = 1;
	while (1) {
		minv = MAXNUM;
		int u = -1;
		for (int i = 0; i < n; i++) {
			if (w[i] < minv && color[i] != 2) {
				u = i;
				minv = w[i];
			}
		}
		if (u == -1) break;
		color[u] = 2;
		for (int i = 0; i < n; i++) {
			if (color[i] != 2 && M[u][i] != MAXNUM) {
				if (w[i] > w[u] + M[u][i]) {
					w[i] = w[u] + M[u][i];
					color[i] = 1;
				}
			}
		}
	}
}

int main() {
	int u, k, v, c;
	cin >> n;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			M[i][j] = MAXNUM;
		}
	}
	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		for (int j = 0; j < k; j++) {
			cin >> v >> c;
			M[u][v] = c;
		}
	}
	dijkstra();
	for (int i = 0; i < n; i++) {
		cout << i << " ";
		if (w[i] != MAXNUM) {
			cout << w[i] << endl;
		}
	}
}