Go: package main

import (
	"bufio"
	"container/heap"
	"fmt"
	"os"
	"strconv"
)

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
const INF = 1 << 60

type Edge struct {
	to, cost int
}

type Node struct {
	id, cost int
}

type PQ []Node

func (pq PQ) Len() int           { return len(pq) }
func (pq PQ) Less(i, j int) bool { return pq[i].cost < pq[j].cost }
func (pq PQ) Swap(i, j int)      { pq[i], pq[j] = pq[j], pq[i] }

func (pq *PQ) Push(x interface{}) {
	*pq = append(*pq, x.(Node))
}

func (pq *PQ) Pop() interface{} {
	old := *pq
	n := len(old)
	x := old[n-1]
	*pq = old[0 : n-1]
	return x
}

func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	E := make([][]Edge, N)
	for i := 0; i < N; i++ {
		id, k := sc.nextInt(), sc.nextInt()
		E[id] = make([]Edge, k)
		for j := 0; j < k; j++ {
			to, cost := sc.nextInt(), sc.nextInt()
			E[id][j] = Edge{to, cost}
		}
	}

	d := make([]int, N)
	for i := 0; i < N; i++ {
		d[i] = INF
	}
	done := make([]bool, N)
	pq := &PQ{}
	heap.Init(pq)
	d[0] = 0
	heap.Push(pq, Node{0, 0})
	for pq.Len() > 0 {
		cur := heap.Pop(pq).(Node).id
		if done[cur] {
			continue
		}
		done[cur] = true
		for i := 0; i < len(E[cur]); i++ {
			to, cost := E[cur][i].to, E[cur][i].cost+d[cur]
			if !done[to] && cost < d[to] {
				d[to] = cost
				heap.Push(pq, Node{to, cost})
			}
		}
	}

	for i := 0; i < N; i++ {
		fmt.Fprintln(wtr, i, d[i])
	}
	wtr.Flush()
}

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

const int INF = 1e8;

int n, m; // 頂点の数、辺の数

struct edge {int from, to, cost;}; // 辺の始点・終点・重み

vector<vector<int>> adj_matrix; // 隣接行列
vector<vector<edge>> adj_list; // 隣接リスト

vector<int> dist;
vector<bool> visited;

void dijkstra(int start) {
    dist.resize(n);
    visited.resize(n);
    rep(i, n) {
        if (i == start) dist[i] = 0;
        else dist[i] = INF;
        visited[i] = false;
    }
    priority_queue<pair<int,int>, vector<pair<int,int>>, greater<pair<int,int>>> pq;
    pq.push({dist[start], start});
    while (not pq.empty()) {
        int cur = pq.top().second;
        pq.pop();
        visited[cur] = true;
        for (edge e : adj_list[cur]) {
            // int adj = e.to;
            if (visited[e.to] == false) {
                if (dist[e.to] > dist[e.from] + e.cost) {
                    dist[e.to] = dist[e.from] + e.cost;
                    pq.push({dist[e.to], e.to});
                }
            }
        }
    }
}

void solve_ALDS1_12_C() {
    cin >> n;
    adj_list.resize(n);
    rep(i, n) {
        int u, k;
        cin >> u;
        cin >> k;
        rep(j, k) {
            edge e;
            e.from = u;
            cin >> e.to;
            cin >> e.cost;
            adj_list[e.from].push_back(e);
        }
    }
    dijkstra(0);
    rep(i, n) {
        cout << i << " " << dist[i] << endl;
    }
}

int main() {
    // cin >> n;
    // cin >> m;
    // adj_matrix.resize(n, vector<int>(n, INF));
    // rep(i, n) {
    //     adj_matrix[i][i] = 0;
    // }
    // adj_list.resize(n);
    // rep(i, m) {
    //     edge e;
    //     cin >> e.from;
    //     cin >> e.to;
    //     cin >> e.cost;
    //     adj_matrix[e.from][e.to] = e.cost;
    //     adj_list[e.from].push_back(e);
    // }
    solve_ALDS1_12_C();
}

C++: #include <bits/stdc++.h>
#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--)
#define INF INT_MAX/3
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define llong long long
#define pb(a) push_back(a)
using namespace std;
typedef pair<int, int> P;
typedef pair<llong, llong> LP;
typedef pair<int, P> PP;
typedef pair<llong, LP> LPP;

int dy[]={0, 0, 1, -1, 0};
int dx[]={1, -1, 0, 0, 0};

#define MAX_N 10000
int G[MAX_N][MAX_N];
int MIN_COSTS[MAX_N];

int main() {
  int n;
  cin >> n;
  REP(i, n) {
    REP(j, n) {
      G[i][j] = INT_MAX;
    }
    MIN_COSTS[i] = INT_MAX;
  }
  int u, k;
  int v, c;
  REP(i, n) {
    cin >> u >> k;
    REP(j, k) {
      cin >> v >> c;
      G[u][v] = c;
    }
  }

  priority_queue<P> q;
  int position;
  int new_cost;
  q.push(P(0, 0));
  while (q.size() != 0){
    position = q.top().first;
    MIN_COSTS[position] = q.top().second;
    q.pop();
    REP(i, n) {
      if (G[position][i] != INT_MAX) {
        new_cost = MIN_COSTS[position] + G[position][i];
        if (new_cost < MIN_COSTS[i]) {
          MIN_COSTS[i] = new_cost;
          q.push(P(i, new_cost));
        }
      }
    }
  }

  REP(i, n) {
    cout << i << ' ' << MIN_COSTS[i] << endl;
  }

  return 0;
}

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

#define N 10001
#define INF 1500001 
int n;

vector<pair<int, int>> A[N];
int color[N];
int d[N];

void dijkstra(int root) {
    priority_queue<pair<int, int>> Q;
    Q.push(make_pair(0, root));

    int treeSize = 1;
    while(!Q.empty()) {
        pair<int, int> addedInfo = Q.top();
        Q.pop();
        int added = addedInfo.second;

        if (color[added] != 1) {
            d[added] = -1 * addedInfo.first;
            color[added] = 1;

            for (vector<pair<int, int>>::iterator it = A[added].begin(); it != A[added].end(); it++) {
                pair<int, int> node_pair = *it;
                if (color[node_pair.first] == 0 && (d[added] + node_pair.second) < d[node_pair.first]) {
                    d[node_pair.first] = d[added] + node_pair.second;
                    Q.push(make_pair(-1 * d[node_pair.first], node_pair.first));
                }
            }
        }
    }
}

int main() {
    cin >> n;

    int w;
    int node;
    int k;
    int ad;
    for (int i = 0; i < n; i++) {
        color[i] = 0;
        d[i] = INF;

        cin >> node >> k;
        for (int j = 0; j < k; j++) {
            cin >> ad >> w;
            A[node].push_back(make_pair(ad, w));
        }
    }

    dijkstra(0);

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

    return 0;
}