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 <vector>
#include <queue>
#include <iostream>

using namespace std;

#define NODE_NUM 10000
#define INF 100000

typedef struct Node {
    //????????????????????????????????????
    int idx;
    
    // ????????????????????????????????¨??????????????±
    vector<int> edges_to;    // ?????¨???????????\?¶??????????????????????
    vector<int> edges_cost;  // ?????¨??????????????????
    
    // ??????????????????????????????????????????
    bool done;  // ?¢??????????????????????
    int cost;   // ????????????????????????????????§??????????????????????°??????????
}Node;

Node nodes[NODE_NUM];


struct NodeCompare
{
    bool operator()(const Node &t1, const Node &t2) const
    {
        //?????????????????????????????????????????????????????????????????????????????´?????????????????????????????????
        return t1.cost > t2.cost;
    }
};

void Dijkstra(int node_num, int start_node){
    
    // ?????????
    for (int i =0 ; i < node_num; i++) {
        nodes[i].done = false;
        nodes[i].cost = INF;
        nodes[i].idx = i;
    }

    //????????????????????\???????°?????????????????????????
    priority_queue<Node, vector<Node>, NodeCompare> q;
    
    // ????????????????????????????????????0
    nodes[start_node].cost = 0;
    q.push(nodes[start_node]);
    
    // ??¢?????´???????????????
    while(!q.empty()){
        
        // ?¢????????????????????????????
        Node doneNode = q.top();
        q.pop();
        
        //???????¢?????????????????????????????????????????????¨??±?????????
        if (doneNode.done) continue;
        
        // ?¢????????????°????????????
        nodes[doneNode.idx].done = true;
        
        // ??\?¶?????????????????????±?????´??°??????
        for(int i = 0; i < doneNode.edges_to.size(); i++){
            
            int to = doneNode.edges_to[i];
            int cost = doneNode.cost + doneNode.edges_cost[i];
            if( nodes[to].cost == INF || cost < nodes[to].cost){
                nodes[to].cost = cost;
                if(!nodes[to].done){
                    q.push(nodes[to]);
                }
            }
        }
    }
}

int main( ){
    
    int i, j, n, k, v, c, u;
    scanf("%d", &n);

    for (i = 0; i < n; i++) {
        scanf("%d %d",&u,  &k);
        
        for (j =0 ; j < k; j++) {
            scanf("%d %d", &v, &c);
            nodes[u].edges_cost.push_back(c);
            nodes[u].edges_to.push_back(v);
        }
    }
    
    Dijkstra(n, 0);
    
    for (i=0; i<n; i++) {
        printf("%d %d\n", i, nodes[i].cost);
    }
    
    return 0;
}

C++: // ALDS1_12_C.cpp
// Graph II - Single Source Shortest Path II
#include <iostream>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <queue>
using namespace std;

struct Node {
    int v;
    int c;
    Node(int v, int c): v(v), c(c) {}
};

const int maxN = 10000;
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;
static const int INF = (1<<21);
vector<Node> G[maxN];
vector<int> dist(maxN, INF);
vector<int> p(maxN);
vector<int> color(maxN, WHITE);
priority_queue<pair<int, int>> mq;
int n;

void dijkstra(int x)
{
    dist[x] = 0;
    p[x] = -1;
    mq.push({-dist[x], x});
    while(!mq.empty()) {
        pair<int, int> P = mq.top();
        mq.pop();
        int mindist = -P.first;
        int u = P.second;
        if (color[u] == BLACK) continue;

        for (int i = 0; i < G[u].size(); i++) {
            if (color[u] == BLACK) continue;
            int v = G[u][i].v;
            int c = G[u][i].c;
            if (dist[u] + c < dist[v]) {
                dist[v] = dist[u] + c;
                p[v] = u;
                color[v] = GRAY;
                mq.push({-dist[v], v});
            }
        }
        color[u] = BLACK;
    }
}

int main()
{
//    freopen("in7.txt", "r", stdin);
//    freopen("out7.txt", "w", stdout);
    cin >> n;
    int u, k;
    int v, c;
    for (int i = 0; i < n; i++) {
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            cin >> v >> c;
            G[i].push_back(Node(v, c));
        }
    }
    dijkstra(0);
    for (int i = 0; i < n; i++) {
        printf("%d %d\n", i, dist[i]);
    }
    return 0;
}