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 <iostream>
#include <iomanip>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <functional>
#include <utility>
#include <tuple>
#include <cctype>
#define INF 0x3f3f3f3f
#define MOD 1000000007
#define PI 4*atan(1.0)
typedef long long ll;
typedef long double ld;
using namespace std;
int dx[4]={0,0,-1,1};
int dy[4]={-1,1,0,0};
const int SIZE=200001+5000;
//int arr[SIZE]={};
//???????????§???????????¬
#define REP(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(auto i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
typedef int Weight;
struct Edge {
  int src, dst;
  Weight weight;
  Edge(int src, int dst, Weight weight) :
    src(src), dst(dst), weight(weight) { }
};
bool operator < (const Edge &e, const Edge &f) {
  return e.weight != f.weight ? e.weight > f.weight : // !!INVERSE!!
    e.src != f.src ? e.src < f.src : e.dst < f.dst;
}
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

typedef vector<Weight> Array;
typedef vector<Array> Matrix;
void shortestPath(const Graph &g, int s,
    vector<Weight> &dist, vector<int> &prev) {
  int n = g.size();
  dist.assign(n, INF); dist[s] = 0;
  prev.assign(n, -1);
  priority_queue<Edge> Q; // "e < f" <=> "e.weight > f.weight"
  for (Q.push(Edge(-2, s, 0)); !Q.empty(); ) {
    Edge e = Q.top(); Q.pop();
    if (prev[e.dst] != -1) continue;
    prev[e.dst] = e.src;
    FOR(f,g[e.dst]) {
      if (dist[f->dst] > e.weight+f->weight) {
        dist[f->dst] = e.weight+f->weight;
        Q.push(Edge(f->src, f->dst, e.weight+f->weight));
      }
    }
  }
}
vector<int> buildPath(const vector<int> &prev, int t) {
  vector<int> path;
  for (int u = t; u >= 0; u = prev[u])
    path.push_back(u);
  reverse(path.begin(), path.end());
  return path;
}
int main(){
	Graph G;
	int N;
	cin>>N;
	for(int i=0;i<N;i++){
		Edges E;
		G.push_back(E);
	}
	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> dist;
	vector<int> prev;
	shortestPath(G,0,dist,prev);
	for(int i=0;i<N;i++){
		cout<<i<<" "<<dist[i]<<endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> P;

int n;
const int MAX = 110;
const int INF = 1e9;
int D[MAX];
struct edge{
    int cost, to;
};
vector<edge> G[MAX];

void dijkstra(int s){
    for(int i = 0; i < n; i++){
        D[i] = INF;
    }
    D[s] = 0;
    priority_queue<P, vector<P>, greater<P>> q;
    q.push({0, s});
    while(!q.empty()){
        P p = q.top();
        q.pop();
        int now = p.second;
        for(int i = 0; i < G[now].size(); i++){
            edge e = G[now][i];
            if(D[e.to] > D[now] + e.cost){
                D[e.to] = D[now] + e.cost;
                q.push({D[e.to], e.to});
            }
        }
    }
}

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

    cin >> n;
    for(int i = 0; i < n; i++){
        int u, k;
        cin >> u >> k;
        for(int i = 0; i < k; i++){
            int v, c;
            cin >> v >> c;
            G[u].push_back({c, v});
        }
    }

    dijkstra(0);

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

    return 0;
}

C++: #define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstdlib>
#include <string>
#include <iostream>
#include <climits>
#include <list>
#include <queue>

using namespace std;

static const int INFTY = -1;

int H;
int A[10001];
int NodeNum[10001];
int IndexInA[10000];


int parent(int i) {
	return i / 2;
}

int left(int i) {
	return 2 * i;
}

int right(int i) {
	return 2 * i + 1;
}

void minHeapify(int i) {
	int l = left(i);
	int r = right(i);
	int smallest = i;
	if (l <= H && A[l] < A[i]) {
		smallest = l;
	}
	if (r <= H && A[r] < A[smallest]) {
		smallest = r;
	}
	if (smallest != i) {
		int temp = A[i];
		A[i] = A[smallest];
		A[smallest] = temp;
		temp = NodeNum[i];
		NodeNum[i] = NodeNum[smallest];
		NodeNum[smallest] = temp;
		IndexInA[NodeNum[i]] = i;
		IndexInA[NodeNum[smallest]] = smallest;

		minHeapify(smallest);
	}
}

void insert(int d, int nodeNum) {
	int i = ++H;
	A[i] = d;
	NodeNum[i] = nodeNum;
	IndexInA[nodeNum] = i;
	int p = parent(i);
	while (i > 1 && A[p] > A[i]) {
		int temp = A[p];
		A[p] = A[i];
		A[i] = temp;
		temp = NodeNum[p];
		NodeNum[p] = NodeNum[i];
		NodeNum[i] = temp;
		IndexInA[NodeNum[p]] = p;
		IndexInA[NodeNum[i]] = i;
		i = p;
		p = parent(i);
	}
}

int heapExtractMinNodeNum() {
	int minNodeNum = NodeNum[1];
	A[1] = A[H];
	NodeNum[1] = NodeNum[H];
	IndexInA[NodeNum[1]] = 1;
	H--;
	minHeapify(1);

	return minNodeNum;
}

void decrese(int i, int value) {
	A[i] = value;
	int p = parent(i);
	while (i > 1 && A[p] > A[i]) {
		int temp = A[p];
		A[p] = A[i];
		A[i] = temp;
		temp = NodeNum[p];
		NodeNum[p] = NodeNum[i];
		NodeNum[i] = temp;
		IndexInA[NodeNum[p]] = p;
		IndexInA[NodeNum[i]] = i;
		i = p;
		p = parent(i);
	}
}

int main() {
	int Dist[10000];
	int AdjacenceyList[10000][10000];
	int AdjacenceyWeightList[10000][10000];
	int Degree[10000];
	int i, j;
	int N;
	int W;
	//int Deg;
	//int MinTotalWeight = 0;
	int u, v;
	int k;
	bool inT[10000];

	cin >> N;

	//for (i = 0; i < N; i++) {
	//	inT[i] = false;
	//	Dist[i] = INFTY;
	//	Deg = -1;
	//	for (j = 0; j < N; j++) {
	//		cin >> W;
	//		if (W != -1) {
	//			AdjacenceyList[i][++Deg] = j;
	//			AdjacenceyWeightList[i][Deg] = W;
	//		}
	//	}
	//	Degree[i] = Deg + 1;
	//}

	for (i = 0; i < N; i++) {
		inT[i] = false;
		Dist[i] = INFTY;
		cin >> u >> k;
		Degree[u] = k;
		for (j = 0; j < k; j++) {
			cin >> AdjacenceyList[u][j] >> AdjacenceyWeightList[u][j];
		}
	}


	H = 0;
	u = 0;
	inT[u] = true;
	Dist[u] = 0;
	for (i = 1; i <= N - 1; i++) {
		for (j = 0; j < Degree[u]; j++) {
			v = AdjacenceyList[u][j];
			if (inT[v] == false) {
				W = AdjacenceyWeightList[u][j];
				if (Dist[v] == INFTY) {
					//Dist[v] = W;
					//insert(W, v);
					Dist[v] = Dist[u] + W;
					insert(Dist[v], v);
				}
				//else if (W < Dist[v]) {
				else if(W + Dist[u] < Dist[v]){
					//Dist[v] = W;
					//decrese(IndexInA[v], W);
					Dist[v] = W + Dist[u];
					decrese(IndexInA[v], Dist[v]);
				}
			}
		}

		int minNodeNum = heapExtractMinNodeNum();
		inT[minNodeNum] = true;
		//MinTotalWeight += Dist[minNodeNum];
		u = minNodeNum;

	}

	//printf("%d\n", MinTotalWeight);

	for (i = 0; i < N; i++) {
		printf("%d %d\n", i, Dist[i]);
	}

	return 0;
}