Go: package main

import (
	"strconv"
	"fmt"
	"bufio"
	"os"
)
const INF = 1 << 21
var scanner = bufio.NewScanner(os.Stdin)

func nextInt() int {
	scanner.Scan()
	i, e := strconv.Atoi(scanner.Text())
	if e != nil {
		panic(e)
	}
	return i
}


func main() {
	scanner.Split(bufio.ScanWords)
	n := nextInt()
	adj := make([][]int, n)
	for i := range adj {
		adj[i] = make([]int, n)
	}

	for i := 0;i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			v := nextInt()
			c := nextInt()
			adj[u][v] = c
		}
	}

	// for i := range adj {
	// 	fmt.Println(adj[i])
	// }

	dist := make([]int, n)
	prev := make([]int, n)
	visited := make([]bool, n)
	dijkstra := func(start int, size int) {
		for i := 0; i < size; i++ {
			dist[i] = INF
			prev[i] = -1
			visited[i] = false
		}
		dist[start] = 0
		for {
			u := -1
			tmp_min := INF
			for i := 0; i < size; i++ {
				if visited[i] == false && dist[i] < tmp_min {
					tmp_min = dist[i]
					u = i
				}
			}
			if u == -1 {
				break
			}
			visited[u] = true
			for i := 0; i < size; i++ {
				if adj[u][i] > 0 {
					w := adj[u][i]
					newlen := dist[u] + w
					if newlen < dist[i] {
						dist[i] = newlen
						prev[i] = u
					}
				}
			}
		}
	}
	dijkstra(0, n)
	for i, cost := range dist {
		fmt.Printf("%d %d\n", i, cost)
	}
}

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;
}

C++: #include<iostream>
#include<iomanip>
#include<algorithm>
#include<bitset>
#include<cassert>
#include<cctype>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<numeric>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<queue>
#include<vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;

#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL

#define MAX 100

using Weight = int;
struct Edge {
	int s; //source
	int d; //destination
	Weight w; //weight
	Edge(int s, int d, int w) : s(s), d(d), w(w) {};
};
using Edges = vector<Edge>;
//???????????\???
//g[u].push_back(Edge(u, v, c));
using Graph = vector<Edges>;
using Array = vector<Weight>;
using Matrix = vector<Array>;

//?????¢?´¢, ??¢?´¢???, ??¢?´¢???
enum { WHITE, GRAY, BLACK };

//???????§????????????? (Dijkstra)
//?????????: ??????????????§????????¢
vector<Weight> dijkstra(Graph g, int s) {
	typedef pair<Weight, int> State; //?§?????????????????°?????????? ??????id
	priority_queue<State, vector<State>, greater<State> >PQ;
	vector<int> color(g.size(), WHITE);
	vector<Weight> dist(g.size(), INF); //distance
	dist[s] = 0; PQ.push(State(0, s)); color[s] = GRAY; //?§????
	while (!PQ.empty()) {
		Weight d; int v;
		tie(d, v) = PQ.top(); PQ.pop(); //dist???????°??????¨??????????´????????????????	
		if (dist[v] < d) continue; //?????§???????????§???????????°??????
		color[v] = BLACK;
		for (auto e : g[v]) { //??£??\????????????????????¨????????????		
			if (color[e.d] == BLACK)continue; //??¢?´¢????????????
			if (dist[e.d] > dist[v] + e.w) {
				dist[e.d] = dist[v] + e.w;
				PQ.push(State(dist[e.d], e.d));
				color[e.d] = GRAY;
			}
		}
	}
	return dist;
}

int main() {
	int n; cin >> n;
	Graph g(n);
	for (int i = 0; i < n; i++) {
		int u, k; cin >> u >> k;
		for (int j = 0; j < k; j++) {
			int v, c; cin >> v >> c;
			g[u].push_back(Edge(u, v, c));
		}
	}
	vector<Weight> ans = dijkstra(g, 0);
	for (int i = 0; i < n; i++) {
		cout << i << " " << ans[i] << endl;
	}
	return 0;
}