Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

const BIG_COST = 200000

type Path struct {
	node int
	cost int
}

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

	nNodes := scanInt(sc)

	// 各頂点につながる頂点一覧を得るための隣接リスト
	graph := make([][]Path, nNodes)

	for i := 0; i < nNodes; i++ {
		u := scanInt(sc)
		k := scanInt(sc)
		graph[i] = make([]Path, k)
		for d := 0; d < k; d++ {
			graph[u][d] = Path{
				node: scanInt(sc),
				cost: scanInt(sc),
			}
		}
	}

	// 0 から各頂点への最小コストを保存する配列
	minCosts := make([]int, nNodes)

	minCosts[0] = 0
	for i := 1; i < nNodes; i++ {
		minCosts[i] = BIG_COST
	}

	// 各頂点が調査済みかどうかを保持する配列
	checked := make([]bool, nNodes)

	// 最小コストのパスを高速に取得するためのヒープ。
	// コストが小さいものほどルートに来るようにする。
	heap := NewHeap(func(a, b Path) bool {
		return a.cost < b.cost
	})

	heap.insert(Path{node: 0, cost: 0})
	for heap.size > 0 {
		u := heap.extractMax()

		// 隣接行列を使っていた時とは違い、ヒープには
		// 同じノードへのパスが複数含まれうる。そのため既によりコストの低い
		// パスが見つかっている場合は無視する。
		if minCosts[u.node] < u.cost {
			continue
		}

		checked[u.node] = true

		for _, v := range graph[u.node] {
			cost := v.cost + u.cost
			if !checked[v.node] && cost < minCosts[v.node] {
				minCosts[v.node] = cost
				heap.insert(Path{node: v.node, cost: cost})
			}
		}
	}

	w := bufio.NewWriter(os.Stdout)
	for i, cost := range minCosts {
		fmt.Fprintf(w, "%d %d\n", i, cost)
	}
	w.Flush()
}

func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

// --- From ALDS1_9_C: Priority Queue

type Heap struct {
	size   int
	heap   []Path
	isHigh func(a, b Path) bool
}

func NewHeap(isHigh func(a, b Path) bool) Heap {
	heap := make([]Path, 1) // 先頭は不使用
	return Heap{size: 0, heap: heap, isHigh: isHigh}
}

func (h *Heap) insert(v Path) {
	h.size += 1
	if h.size > len(h.heap)-1 {
		h.heap = append(h.heap, v)
	} else {
		h.heap[h.size] = v
	}

	for i := h.size; i > 1; {
		parent := i / 2
		if h.isHigh(h.heap[parent], h.heap[i]) {
			break
		}
		h.heap[i], h.heap[parent] = h.heap[parent], h.heap[i]
		i = parent
	}
}

func (h *Heap) extractMax() Path {
	if h.size <= 0 {
		panic("cannot extract from empty heap")
	}

	max := h.heap[1]
	h.heap[1] = h.heap[h.size]
	h.size -= 1
	h.maxHeapify(1)

	return max
}

func (h *Heap) maxHeapify(idx int) {
	left := idx * 2
	right := left + 1
	largest := idx

	if left <= h.size {
		if h.isHigh(h.heap[left], h.heap[idx]) {
			largest = left
		}
		if right <= h.size && h.isHigh(h.heap[right], h.heap[largest]) {
			largest = right
		}
	}

	if largest != idx {
		h.heap[idx], h.heap[largest] = h.heap[largest], h.heap[idx]
		h.maxHeapify(largest)
	}
}

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

using namespace std;

vector<int> adja[10000], cost[10000];

#define INF (1 << 30)

int main() {
	int n, id, k;

	cin >> n;
	for (int i = 0; i < n; ++i) {
		cin >> id >> k;
		adja[id].resize(k);
		cost[id].resize(k);
		for (int j = 0; j < k; ++j) {
			cin >> adja[id][j] >> cost[id][j];
		}
	}

	priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> que;
	que.push(make_pair(0, 0)); //cost, node
	int best[10000];
	fill(best, best + n, INF);
	best[0] = 0;

	while (!que.empty()) {
		pair<int, int> top = que.top();
		que.pop();

		if (best[top.second] < top.first) {
			continue;
		}

		for (int j = 0, len = adja[top.second].size(); j < len; ++j) {
			if (best[adja[top.second][j]] > top.first + cost[top.second][j]) {
				best[adja[top.second][j]] = top.first + cost[top.second][j];
				que.push(make_pair(top.first + cost[top.second][j], adja[top.second][j]));
			}
		}
	}

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

	return 0;
}

C++: #include <map>
#include <set>
#include <list>
#include <cmath>
#include <deque>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <numeric>
#include <utility>
#include <iostream>
#include <algorithm>
#include <functional>
#include <unordered_map>
#include <unordered_set>

using namespace std;

#define ll long long
#define ull unsigned long long
#define INF (1 << 30)
#define LLINF (1LL << 62)
#define MOD7 1000000007
#define MOD9 1000000009
#define eps 1e-9
#define P pair<int, int>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pul pair<ull, ull>
#define all(a) (a).begin(), (a).end()
#define FOR(i,a,b) for (int i=(a);i<(b);++i)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);--i)
#define REP(i,n) for (int i=0;i<(n);++i)
#define RREP(i,n) for (int i=(n)-1;i>=0;--i)

void YES() { cout << "YES" << endl; }
void NO() { cout << "NO" << endl; }
void Yes() { cout << "Yes" << endl; }
void No() { cout << "No" << endl; }
void yes() { cout << "yes" << endl; }
void no() { cout << "no" << endl; }

template<class T>
class Graph {
public:
	class Edge {
	public:
		int to;
		T cost;

		Edge(int t, T c) : to(t), cost(c) {}
	};

	vector<vector<Edge>> G;
	int V;

	Graph(int n = 0) {
		resize(n);
	}

	void resize(int n) {
		V = n;
		G.resize(n);
	}

	void addEdge(int from, int to, T cost = 0) {
		int v = max(from, to);
		if (v >= V)
			resize(v + 1);
		G[from].push_back(Edge(to, cost));
	}

	void dfs(int s) {
		vector<int> visit(V);
		calcDfs(visit, s);
	}

	void calcDfs(vector<int>& visit, int s) {
		if (visit[s])
			return;

		visit[s] = 1;
		for (int i = 0; i < G[s].size(); ++i) {
			calcDfs(visit, G[s][i].to);
		}
	}

	vector<T> bfs(int s) {
		vector<T> dist(V);
		queue<int> que;

		fill(dist.begin(), dist.end(), -1);
		dist[s] = 0;
		que.push(s);
		while (!que.empty()) {
			int from = que.front();
			que.pop();
			for (int i = 0; i < G[from].size(); ++i) {
				int to = G[from][i].to;
				if (dist[to] != -1)
					continue;
				dist[to] = dist[from] + G[from][i].cost;
				que.push(to);
			}
		}

		return dist;
	}

	vector<T> dijkstra(int s) {
		vector<T> dist(V);	
		priority_queue<pair<T, int>, vector<pair<T, int>>, greater<pair<T, int>>> que;
		
		fill(dist.begin(), dist.end(), INF);
		dist[s] = 0;
		que.push(make_pair(0, s));
		while (!que.empty()) {
			auto f = que.top();
			que.pop();

			T cost = f.first;
			int from = f.second;

			for (int i = 0; i < G[from].size(); ++i) {
				int to = G[from][i].to;
				if (dist[to] > cost + G[from][i].cost) {
					dist[to] = cost + G[from][i].cost;
					que.push(make_pair(dist[to], to));
				}
			}
		}

		return dist;
	}

	T prim() {
		int s = -1;
		for (int i = 0; i < V; ++i) {
			if (G[i].size() > 0) {
				s = i;
				break;
			}
		}

		T dst = 0;
		vector<int> visit(V);
		priority_queue<pair<T, int>, vector<pair<T, int>>, greater<pair<T, int>>> que;
		que.push(make_pair(0, s));
		while (!que.empty()) {
			auto from = que.top();
			que.pop();

			if (visit[from.second] != 2) {
				dst += from.first;
				visit[from.second] = 2;
			}

			for (int i = 0; i < G[from.second].size(); ++i) {
				auto tmp = G[from.second][i];
				if (visit[tmp.to] != 2) {
					visit[tmp.to] = 1;
					que.push(make_pair(tmp.cost, tmp.to));
				}
			}
		}

		return dst;
	}
};

int main() {
	int n, from, k, to, cost;
	Graph<int> g;
	cin >> n;
	for (int i = 0; i < n; ++i) {
		cin >> from >> k;
		while (k--) {
			cin >> to >> cost;
			g.addEdge(from, to, cost);
		}
	}

	auto v = g.dijkstra(0);

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

	return 0;
}