Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
const INF = 1 << 60

type Edge struct {
	to, cost int
}

type Node struct {
	id, cost int
}

type PQ []Node

func (pq PQ) Len() int           { return len(pq) }
func (pq PQ) Less(i, j int) bool { return pq[i].cost < pq[j].cost }
func (pq PQ) Swap(i, j int)      { pq[i], pq[j] = pq[j], pq[i] }

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

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

func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	E := make([][]Edge, N)
	for i := 0; i < N; i++ {
		id, k := sc.nextInt(), sc.nextInt()
		E[id] = make([]Edge, k)
		for j := 0; j < k; j++ {
			to, cost := sc.nextInt(), sc.nextInt()
			E[id][j] = Edge{to, cost}
		}
	}

	d := make([]int, N)
	for i := 0; i < N; i++ {
		d[i] = INF
	}
	done := make([]bool, N)
	pq := &PQ{}
	heap.Init(pq)
	d[0] = 0
	heap.Push(pq, Node{0, 0})
	for pq.Len() > 0 {
		cur := heap.Pop(pq).(Node).id
		if done[cur] {
			continue
		}
		done[cur] = true
		for i := 0; i < len(E[cur]); i++ {
			to, cost := E[cur][i].to, E[cur][i].cost+d[cur]
			if !done[to] && cost < d[to] {
				d[to] = cost
				heap.Push(pq, Node{to, cost})
			}
		}
	}

	for i := 0; i < N; i++ {
		fmt.Fprintln(wtr, i, d[i])
	}
	wtr.Flush()
}

C++: #include <cstdio>
#include <cctype>
#include <climits>
#include <vector>
using namespace std;

#define si static inline
#define gcu getchar_unlocked
si int in() {
	int n = 0, c = gcu();
	// bool minus = false; if (c == '-') minus = true, c = gcu();
	do {n = 10 * n + (c - '0'), c = gcu();} while (c >= '0');
	return n; }
	// return minus ? -n : n; }
si void scan(char *s) {while (!isspace(*s++ = gcu()));}
#define pcu putchar_unlocked
#define svo si void out
template <typename T>
svo(T n) {
	static char buf[20];
	char *p = buf;
	//if(n < 0) pcu('-'), n *= -1;
	if (!n) *p++ = '0';
	else while (n) *p++ = n % 10 + '0', n /= 10;
	while (p != buf) pcu(*--p); }
svo(const char *s){while(*s)pcu(*s++);}
svo(char *s){while(*s)pcu(*s++);}
svo(char c){pcu(c);}
template <typename T>
//svo(vector<T> &v){for(T &x:v)out(' '),out(x);out('\n');}
svo(vector<T> &v){for(T &x:v)out(&x == &v[0]?"":" "),out(x);out('\n');}
template <typename head, typename... tail>
svo(head&& h, tail&&... t){out(h);out(move(t)...);}
#undef svo
#undef si

template <typename T>
struct heap{
	vector<T> h = {T()};

	void insert(T x) {
		h.push_back(x);
		int c = h.size() - 1;
		for (int p = c / 2; p; c = p, p /= 2)
			if (h[p] < x)
				h[c] = move(h[p]);
			else
				break;
		h[c] = move(x);
	}
	T extract() {
		T res = move(h[1]);
		h[1] = h.back();
		T v = move(h[1]);
		h.pop_back();

		int p = 1, H = h.size();
		for (int c = 2; c < H; p = c, c = p * 2) {
			if (c + 1 < H && h[c] < h[c + 1])
				c++;
			if (h[c] < v)
				break;
			h[p] = move(h[c]);
		}
		h[p] = move(v);

		return move(res);
	}

	bool empty() {
		return h.size() == 1;
	}
};

#define v vector
struct graph {
	struct node {int n, w;};
	v<v<node>> nodes;

	void read(int n) {
		nodes.resize(n);
		for (auto &x: nodes) {
			in();
			for (int k = in(); k--;) {
				int c = in();
				x.push_back({c, in()});
			}
		}
	}

	v<node> dks() {
		v<node> w(nodes.size(), {0, INT_MAX});
		w[0].w = 0;
		heap<node> q;
		q.insert({0, 0});
		while (!q.empty()) {
			node n = q.extract();
			if (w[n.n].n)
				continue;
			w[n.n].n = 1;
			for (node &x: nodes[n.n]) {
				int a = n.w + x.w;
				if (w[x.n].w > a) {
					w[x.n].w = a;
					q.insert({x.n, a});
				}
			}
		}
		return move(w);
	}
};

bool operator < (const graph::node &a, const graph::node &b) {
	return a.w > b.w;
}

int main() {
	graph g;
	g.read(in());
	int i = 0;
	for (auto &x: g.dks())
		out(i++, ' ', x.w, '\n');
}

C++: #include <iostream>
#include <queue>
#include <utility>
#include <vector>

struct Edge {
  int from, to, weight;
  Edge(int from, int to, int weight) : from(from), to(to), weight(weight) {}
};

struct Node {
  std::vector<Edge> ongoingEdges;
  void addEdge(Edge edge) {
    ongoingEdges.push_back(edge);
  }
};

class Graph {
private:
  std::vector<Node> nodes;
  int size;
public:
  Graph(int size): size(size) {
    nodes.resize(size);
  }
  void addEdge(Edge edge) {
    nodes[edge.from].addEdge(edge);
  }

  std::vector<int> calculateDist(int source) {
    std::vector<int> dist(size, (1 << 30));
    std::priority_queue< std::pair<int, int>, std::vector< std::pair<int, int> >, std::greater< std::pair<int, int> > > pq;

    pq.push(std::make_pair(0, source));
    dist[source] = 0;

    while(!pq.empty()) {
      int from = pq.top().second;
      pq.pop();

      for(Edge edge: nodes[from].ongoingEdges) {
        if(dist[edge.to] > dist[from] + edge.weight) {
          dist[edge.to] = dist[from] + edge.weight;
          pq.push({dist[edge.to], edge.to});
        }
      }

    }

    return dist;
  }
};

int main() {
  int n;
  std::cin >> n;
  Graph graph(n);

  for(int i = 0; i < n; i++) {
    int u, k;
    std::cin >> u >> k;

    for(int i = 0; i < k; i++) {
      int v, c;
      std::cin >> v >> c;
      graph.addEdge(Edge(u, v, c));
    }

  }

  std::vector<int> dist = graph.calculateDist(0);

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

}