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;

#define rep(i, n) REP(i, 0, n)
#define REP(i, k, n) for(auto i = k; i != n; i++)
#define rrep(i, n) RREP(i, n, 0)
#define RREP(i, n, k) for(auto i = n; i != k; i--)
#define ALL(x) (x).begin(), (x).end()
#define debug(x) cerr << #x << " " << x << endl
#define in(x, data) (data).find(x) != (data).end()

typedef long long ll;
typedef pair<int, int> PRii;

class Node {
public:
    int dist, number;
    Node(int d, int n) {
        dist = d;
        number = n;
    }
};

bool operator < (const Node &l, const Node &r) {
    return l.dist < r.dist
    || (!(r.dist < l.dist) && l.number < r.number);
};

bool operator > (const Node &l, const Node &r) {
    return r < l;
};

class Edge {
public:
    int to, cost;
    Edge(int t, int c) {
        to = t;
        cost = c;
    }
};

int node_n;
vector<vector<Edge>> edge;
vector<int> d;

void cost_initializer(int n) {
    edge = vector<vector<Edge>>(n, vector<Edge>());
}

void dijkstra(int start_p) {
    d = vector<int>(node_n, INT_MAX); d[start_p] = 0;
    vector<int> prev = vector<int>(node_n);

    priority_queue<Node,vector<Node>,greater<Node>> Q;

    for(int i=0; i<node_n; i++) {
        Q.push(Node(d[i],i));
    }

    while(!Q.empty()) {
        Node u = Q.top(); Q.pop();
        if(u.dist > d[u.number]) continue;
        for(int i=0; i<edge[u.number].size(); i++) {
            int alt = d[u.number] + edge[u.number][i].cost;
            int v = edge[u.number][i].to;
            if(d[v] > alt) {
                d[v] = alt;
                prev[v] = u.number;
                Q.push(Node(d[v],v));
            }
        }
    }
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    int n; cin >> n;
    node_n = n;
    cost_initializer(node_n);

    rep(i,n) {
        int u, k; cin >> u >> k;
        rep(j,k) {
            int v, c; cin >> v >> c;
            edge[u].push_back(Edge(v,c));
        }
    }

    dijkstra(0);
    rep(i,n) cout << i << " " << d[i] << endl;
    return 0;
}

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

#define si static inline
#define gcu getchar_unlocked
si int in() {
	int c, n = 0;
	// bool minus = false; if ((c = gcu()) == '-') minus = true; else ungetc(c, stdin);
	while ((c = gcu()) >= '0' && c <= '9') n = 10 * n + (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<bits/stdc++.h>
#define to first
#define wgt second 

using namespace std;

typedef pair<int,int> pii;
typedef vector<pii> vec;
typedef vector<vec> Graph;

Graph G(11000);
int n,d[11000];

void SPFA()
{
	bool used[11000];
	queue<int> que;
	memset(used,false,sizeof(used));
	fill(d,d+n,INT_MAX);
	d[0]=0;
	que.push(0);
	while(!que.empty())
	{
		int u=que.front();que.pop();
		for(int i=0;i<G[u].size();i++)
			if(d[G[u][i].to]>d[u]+G[u][i].wgt)
			{
				d[G[u][i].to]=d[u]+G[u][i].wgt;
				que.push(G[u][i].to);
			}
	}
}

int main()
{
	scanf("%d",&n);
	for(int i=0;i<n;i++)
	{
		int u,t;
		scanf("%d%d",&u,&t);
		for(int j=0;j<t;j++)
		{
			int v,w;
			scanf("%d%d",&v,&w);
			G[u].push_back(make_pair(v,w));
		}
	}
	SPFA();
	for(int i=0;i<n;i++)
		printf("%d %d\n",i,d[i]);
	return 0;
}