Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

var infty = 1000000000

type DirectedGraphNodeID int

type DirectedGraphNode struct {
	key         DirectedGraphNodeID
	adjacents   []*DirectedGraphNode
	costs       []int
	distance    int
	predecessor *DirectedGraphNode
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]*DirectedGraphNode, nNodes)
	for i := 0; i < nNodes; i++ {
		node := DirectedGraphNode{}
		node.key = DirectedGraphNodeID(i)
		node.distance = infty
		graph.nodes[i] = &node
	}
	return &graph
}

type DirectedGraph struct {
	nodes []*DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(i, j DirectedGraphNodeID, cost int) {
	g.nodes[i].adjacents = append(g.nodes[i].adjacents, g.nodes[j])
	g.nodes[i].costs = append(g.nodes[i].costs, cost)
}

func (g *DirectedGraph) print() {
	for i := 0; i < len(g.nodes); i++ {
		node := g.nodes[i]
		key := node.key
		strings := []string{strconv.Itoa(int(key)), strconv.Itoa(node.distance)}
		for j := 0; j < len(node.adjacents); j++ {
			nodeJ := fmt.Sprintf("(%v, %v)", node.adjacents[j].key, node.costs[j])
			strings = append(strings, nodeJ)
		}
		fmt.Printf("%v\n", strings)
	}
}

func (g *DirectedGraph) relaxEdge(l, r *DirectedGraphNode, w int) {
	if r.distance > l.distance+w {
		// fmt.Printf("%v -> %v, %v\n", l.key, r.key, l.distance+w)
		r.distance = l.distance + w
		r.predecessor = l
	}
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	graph := newDirectedGraph(nNodes)

	for i := 0; i < nNodes; i++ {
		iNode := DirectedGraphNodeID(nextInt())
		nAdjacent := nextInt()
		for j := 0; j < nAdjacent; j++ {
			jNode := DirectedGraphNodeID(nextInt())
			cost := nextInt()
			graph.setAdjacency(iNode, jNode, cost)
		}
	}

	graph.nodes[0].distance = 0
	for iNode := 0; iNode < nNodes; iNode++ {
		for iLeft := 0; iLeft < len(graph.nodes); iLeft++ {
			nodeLeft := graph.nodes[iLeft]
			for iRight := 0; iRight < len(nodeLeft.adjacents); iRight++ {
				nodeRight := nodeLeft.adjacents[iRight]
				cost := nodeLeft.costs[iRight]
				graph.relaxEdge(nodeLeft, nodeRight, cost)
			}
		}
	}

	// graph.print()

	for iNode := 0; iNode < len(graph.nodes); iNode++ {
		node := graph.nodes[iNode]
		fmt.Println(node.key, node.distance)
	}
}

C++: // #include <bits/stdc++.h>
// using namespace std;
// #define rep(i, n) for (int i = 0; i < n; i++)

// int n;
// vector<vector<int>> a(100,vector<int>(100, -1)); // 各頂点間の重みを表す隣接行列
// vector<int> d(100, -1);

// void dijkstra(int start) {
//     vector<int> s;
    
//     s.push_back(start);
//     d[start] = 0;
//     while (s.size() < n) {
//         int min_v = 10000001, min_i;
//         rep(i, s.size()) {
//             int cur = s[i];
//             rep(j, n) {
//                 int adj = a[cur][j];
//                 if (adj != -1 && d[j] == -1 && d[cur] + adj < min_v) {
//                     min_v = d[cur] + adj;
//                     min_i = j;
//                 }
//             }
//         }
//         s.push_back(min_i);
//         d[min_i] = min_v;
//     }
// }

// int main() {
//     scanf("%d", &n);
//     rep(i, n) {
//         int u, k;
//         scanf("%d %d", &u, &k);
//         rep(j, k) {
//             int v, c;
//             scanf("%d %d", &v, &c);
//             a[u][v] = c;
//         }
//     }
//     dijkstra(0);
//     rep(i, n) {
//         printf("%d %d\n", i, d[i]);
//     }
// }

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < n; i++)

const int INF = 1000000000;
int n;
vector<vector<pair<int,int>>> e;
vector<int> d;
vector<bool> t;
void dijkstra(int start) {
    d[start] = 0;
    priority_queue<pair<int,int>, vector<pair<int,int>>, greater<pair<int,int>>> pq;
    pq.push({d[start],start});
    while (not pq.empty()) {
        int u = pq.top().second; // uは最短経路木に含まれない頂点のうちd[u]が最小であるもの
        pq.pop();
        t[u] = true; // uを最短経路木に含ませる
        rep(j, e[u].size()) {
            int v = e[u][j].first; // uの隣接点
            if (t[v] == false) { // 隣接点のうち最短経路木に含まれないもの
                if (d[u] + e[u][j].second < d[v]) { // e[u][j].secondはuから隣接点までの距離
                    d[v] = d[u] + e[u][j].second;
                    pq.push({d[v],v});
                }
            }
        }
    }
}

int main() {
    cin >> n;
    e.resize(n);
    rep(i, n) {
        int u, k;
        cin >> u >> k;
        rep(j, k) {
            int v, c;
            cin >> v >> c;
            e[u].push_back({v,c});
        }
    }
    d.resize(n,INF);
    t.resize(n,false);
    dijkstra(0);
    rep(i, n) {
        printf("%d %d\n", i, d[i]);
    }
}

C++: #include <iostream>
#include <algorithm>
using namespace std;

const int INF = 1 << 29;

int main()
{
    int n,u,k,v,c;
    int V[101][101];
    fill((int*)V, (int*)(V + 101), INF);
    
    cin >> n;
    for(int i = 0; i < n; ++i){
        V[i][i] = 0;
    }
    
    for(int i = 0; i < n; ++i){
        cin >> u >> k;
        for(int j = 0; j < k; ++j){
            cin >> v >> c;
            V[u][v] = c;
        }
    }
    
    for(int k = 0; k < n; ++k){
        for(int i = 0; i < n; ++i){
            for(int j = 0; j < n; ++j){
                V[i][j] = min(V[i][j],V[i][k] + V[k][j]);
            }
        }
    }
    
    for(int i = 0; i < n; ++i){
        cout << i << ' ' << V[0][i] << endl;
    }
    
}

C++: #include <iostream>
using namespace std;

static const int MAX = 100;
static const int INFTY = (1<<21);
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;

int n,M[MAX][MAX];

void dijkstra(){
    int minv;
    int d[MAX],color[MAX];
    
    for(int i=0; i<n; i++){
        d[i] = INFTY;
        color[i] = WHITE;
    }
    
    d[0] = 0;
    color[0] = GRAY;
    while (1) {
        minv = INFTY;
        int u = -1;
        for(int i=0; i<n; i++){
            if(minv > d[i] && color[i] != BLACK){
                u = i;
                minv = d[i];
            }
        }
        if(u==-1) break;
        color[u] = BLACK;
        for(int v=0; v<n; v++){
            if(color[v]!=BLACK && M[u][v]!=INFTY){
                if(d[v] > d[u] + M[u][v]){
                    d[v] = d[u]+M[u][v];
                    color[v] = GRAY;
                }
            }
        }
    }
    for(int i=0; i<n; i++){
        cout << i << " " << (d[i]==INFTY ? -1 : d[i]) << endl;
    }
}

int main(){
    cin >> n;
    for(int i=0; i<n; i++){
        for(int j=0; j<n; j++){
            M[i][j] = INFTY;
        }
    }
    
    int k,c,u,v;
    for(int i=0; i<n; i++){
        cin >> u >> k;
        for(int j=0; j<k; j++){
            cin >> v >> c;
            M[u][v] = c;
        }
    }
    
    dijkstra();
}