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 <iostream>
#include <vector>
#include <array>
#include <algorithm>
#include <limits>
#include <cmath>
#include <numeric>
#include <string>
#include <queue>

using namespace std;

using ll = long long int;
using ull = unsigned long long int;
#define rep(i, a, b) for(int i = (a); i < (b); ++i )
#define rrep(i, a, b) for(int i = (a); i > (b); --i )
#define REP(i, a, b) for(int i = (a); i <= (b); ++i )
#define RREP(i, a, b) for(int i = (a); i >= (b); --i )
#define llrep(i, a, b) for(ll i = (a); i < (b); ++i )
#define llrrep(i, a, b) for(ll i = (a); i > (b); --i )
#define llREP(i, a, b) for(ll i = (a); i <= (b); ++i )
#define llRREP(i, a, b) for(ll i = (a); i >= (b); --i )
#define ullrep(i, a, b) for(ull i = (a); i < (b); ++i )
#define ullrrep(i, a, b) for(ull i = (a); i > (b); --i )
#define ullREP(i, a, b) for(ull i = (a); i <= (b); ++i )
#define ullRREP(i, a, b) for(ull i = (a); i >= (b); --i )

template<typename T=int>
class UnionFind {
public:
    explicit UnionFind(unsigned long long n) : rank_(n, 0), p_(n, 0) {
        for (T i = 0; i < n; i++) {
            MakeSet(i);
        }
    }

    void MakeSet(T x) {
        p_[x] = x;
        rank_[x] = 0;
    }

    bool Same(T x, T y) {
        return FindSet(x) == FindSet(y);
    }

    void Link(T x, T y) {
        if (rank_[x] > rank_[y]) {
            p_[y] = x;
        } else {
            p_[x] = y;
            if (rank_[x] == rank_[y]) {
                rank_[y]++;
            }
        }
    }

    void Unite(T x, T y) {
        Link(FindSet(x), FindSet(y));
    }

    T FindSet(T x) {
        if (x != p_[x]) {
            p_[x] = FindSet(p_[x]);
        }
        return p_[x];
    }

private:
    std::vector<T> rank_, p_;
};

// 隣接行列を使ったダイクストラ
class Dijkstra {
public:
    Dijkstra(unsigned long long num, int max_cost) :
            num_(num),
            max_cost_(max_cost),
            v_(num, std::vector<int>(num, max_cost)),
            c_(num, 0),
            d_(num, max_cost),
            p_(num, 0) {
    };

    void Compute(int start) {
        d_[start] = 0;
        p_[start] = start;
        while (true) {
            int m = -1;
            int min_d = std::numeric_limits<int>::max();
            for (int i = 0; i < num_; i++) {
                if ((c_[i] == 0) && (min_d > d_[i])) {
                    min_d = d_[i];
                    m = i;
                }
            }
            if (m < 0) {
                break;
            }
            c_[m] = 1;
            for (int i = 0; i < num_; i++) {
                if ((c_[i] == 0) && (d_[i] > (d_[m] + v_[m][i])) ) {
                    d_[i] = d_[m] + v_[m][i];
                    p_[i] = m;
                }
            }
        }
    }

public:
    int num_;
    int max_cost_;
    std::vector<std::vector<int>> v_;
    std::vector<int> c_;
    std::vector<int> d_;
    std::vector<int> p_;
};

class DijkstraQueue {
public:
    DijkstraQueue(unsigned long long num, int max_cost):
            num_(num),
            adj_(num),
            c_(num, 0),
            d_(num, max_cost),
            p_(num, 0)
    {}

    void Compute(int start) {
        std::priority_queue<std::pair<int, int>> pq;
        d_[start] = 0;
        pq.push(std::make_pair(0, start));
        while (!pq.empty()) {
            auto f = pq.top();// cost, i
            pq.pop();
            int u = f.second;
            c_[u] = 1;
            if (d_[u] < f.first * (-1)) {
                continue;
            }

            for(int j = 0; j < adj_[u].size(); j++) {
                int v = adj_[u][j].first;
                if (c_[v] == 1) 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));
                }
            }
        }
    }
    int num_;
    std::vector<std::vector<std::pair<int, int>>> adj_; //i, cost
    std::vector<int> c_;
    std::vector<int> d_;
    std::vector<int> p_;
};




int N, Q;

int G[100][100];
int d[100];
int p[100];
int c[100];

int main() {
    cin >> N;
//    rep(i, 0, N) {
//        rep(j, 0, N) {
//            G[i][j] = 10000010;
//        }
//    }
//    Dijkstra dj(N, 10000010);
    DijkstraQueue dj(N, 10000010);
    rep(i, 0, N) {
        int u, k;
        cin >> u >> k;
        rep(j, 0, k) {
            int t, d;
            cin >> t >> d;
            dj.adj_[u].push_back(make_pair(t, d));
        }
    }
    dj.Compute(0);
    rep(i, 0, N) {
        cout << i << " " << dj.d_[i] << endl;
    }
}