Go: package main

import (
	"bufio"
	"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
type Node struct {
	cost int
	done bool
}

type Edge struct {
	to, cost int
}

const INF = 1 << 60

func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	nodes := make([]Node, N)
	for i := 0; i < N; i++ {
		nodes[i].cost = INF
	}
	E := make([][]Edge, N)
	for i := 0; i < N; i++ {
		id, k := sc.nextInt(), sc.nextInt()
		for j := 0; j < k; j++ {
			to, cost := sc.nextInt(), sc.nextInt()
			E[id] = append(E[id], Edge{to, cost})
		}
	}
	nodes[0].cost = 0
	for {
		cur := 0
		minCost := INF
		for i := 0; i < N; i++ {
			n := nodes[i]
			if !n.done && n.cost < minCost {
				cur = i
				minCost = n.cost
			}
		}
		if minCost == INF {
			break
		}
		nodes[cur].done = true
		for i := 0; i < len(E[cur]); i++ {
			to, cost := E[cur][i].to, E[cur][i].cost+nodes[cur].cost
			if !nodes[to].done && cost < nodes[to].cost {
				nodes[to].cost = cost
			}
		}
	}

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

C++: #include <stdio.h>
#include <stdint.h>
#include <iostream>
#include <fstream>
#include <cassert>
#include <climits>

#include <queue>
#include <memory>
using namespace std;

#define DEBUG (0)

#if DEBUG
#define DPRINTF(...) do { \
    printf("D(L%d) %s: ", __LINE__, __func__); \
    printf(__VA_ARGS__); \
  } while (false)
#else
#define DPRINTF(...)
#endif // DEBUG


const int kMaxVertex = 100;
int g_num_of_vertex;
int g_min_weight[kMaxVertex];


enum State {
    kUnvisited = 0,
    kVisited,
};


struct Edge {
    Edge(int num_vertex)
        : num_vertex_(num_vertex)
    {
        const int size_of_ptr_ = num_vertex_ * num_vertex_;
        weight_ = unique_ptr<int>(new int[size_of_ptr_]);

        for (int i = 0; i < num_vertex_; i++)
            for (int j = 0; j < num_vertex_; j++)
                setWeight(i, j, kInvalidWeight);

        for (int i = 0; i < num_vertex_; i++)
            setWeight(i, i, 0);
    }

    const int kInvalidWeight = INT_MAX;

    bool isConnected(int v0, int v1) const;
    vector<int> getConnectedVertices(int v) const;
    int getWeight(int v0, int v1) const;
    void setWeight(int v0, int v1, int w);

    void printWeight() const;

    int num_vertex_;
    int size_of_ptr_;
    unique_ptr<int> weight_;
};

bool Edge::isConnected(int v0, int v1) const
{
    if (v0 == v1)
        return false;

    if (getWeight(v0, v1) == kInvalidWeight)
        return false;

    return true;
}

vector<int> Edge::getConnectedVertices(int v) const
{
    vector<int> vertices;

    for (int i = 0; i < num_vertex_; i++)
        if (isConnected(v, i))
            vertices.push_back(i);

    return vertices;
}

void Edge::setWeight(int v0, int v1, int w)
{
    assert(0 <= v0 && v0 < num_vertex_);
    assert(0 <= v1 && v1 < num_vertex_);

    int *p = weight_.get() + (v0 * num_vertex_) + v1;
    *p = w;
}

int Edge::getWeight(int v0, int v1) const
{
    int *p = weight_.get() + (v0 * num_vertex_) + v1;
    return *p;
}

void Edge::printWeight() const
{
    DPRINTF("\n");
    for (int i = 0; i < num_vertex_; i++)
    {
        printf("    [%d]", i);
        for (int j = 0; j < num_vertex_; j++)
        {
            printf(" %d", getWeight(i, j));
        }
        cout << endl;
    }
}


struct VtxAndWeight {
    VtxAndWeight(int vtx, int weight)
        : vtx_(vtx)
        , weight_(weight)
    {}

    int vtx_;
    int weight_;
};


void calcShortestPath(int start, const Edge &edge)
{
    DPRINTF("start %d\n", start);
    assert(0 <= start && start < g_num_of_vertex);

    int current = start;
    int weight = 0;

    queue<VtxAndWeight> que;
    que.push(VtxAndWeight(current, weight));

    while (!que.empty())
    {
        VtxAndWeight vw = que.front();
        que.pop();

        int vtx = vw.vtx_;
        int weight = vw.weight_;

        DPRINTF("vtx %d  weight %d\n", vtx, weight);

        if (weight > g_min_weight[vtx])
        {
            continue;
        }
        g_min_weight[vtx] = weight;

        vector<int> connectedVertices = edge.getConnectedVertices(vtx);

        // update weight
        // push to queue as the next vertex to be visited
        for (int next_vtx : connectedVertices)
        {
            int next_weight = weight + edge.getWeight(vtx, next_vtx);
DPRINTF("next_vtx %d  next_weight %d\n", next_vtx, next_weight);
            que.push(VtxAndWeight(next_vtx, next_weight));
        }

    }

}


int main()
{
    cin >> g_num_of_vertex;
    cin.ignore();

    // init
    for (int i = 0; i < g_num_of_vertex; i++)
    {
        g_min_weight[i] = INT_MAX;
    }

    Edge edge(g_num_of_vertex);

    // input
    for (int i = 0; i < g_num_of_vertex; i++)
    {
        int start, degree;
        cin >> start >> degree;

        for (int j = 0; j < degree; j++)
        {
            int dst, weight;
            cin >> dst >> weight;

            edge.setWeight(start, dst, weight);
        }

        cin.ignore();
    }

#if DEBUG
    edge.printWeight();
#endif

    // process
    const int start = 0;
    calcShortestPath(start, edge);

    // output
    for (int i = 0; i < g_num_of_vertex; i++)
        printf("%d %d\n", i, g_min_weight[i]);

    return 0;
}

C++: #include <iostream>
#define WHITE 0
#define GRAY 1
#define BLACK 2
#define MAX_N 101
#define INF 100000000
using namespace std;

int m[MAX_N][MAX_N];
int d[MAX_N];
int color[MAX_N];

void dijkstra(int s, int n) {
  for (int i = 0; i < n; i++) {
    d[i] = INF;
    color[i] = WHITE;
  }

  d[s] = 0;
  color[s] = GRAY;

  while (true) {
    int mincost = INF;
    int u = -1;
    for (int i = 0; i < n; i++) {
      if (color[i] != BLACK && d[i] < mincost) {
	mincost = d[i];
	u = i;
      }
    }
    
    if (mincost == INF) break;
    
    color[u] = BLACK;
    for (int v = 0; v < n; v++) {
      if (color[v] != BLACK && m[u][v] != INF) {
	if (d[u] + m[u][v] < d[v]) {
	  d[v] = d[u] + m[u][v];
	  color[v] = GRAY;
	}
      }
    }
  }
}

void init(int n) {
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      m[i][j] = INF;
    }
  }
}

int main() {
  int n;
  cin >> n;

  init(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;
      m[u][v] = c;
    }
  }

  dijkstra(0, n);

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

  return 0;
}