Go: package main

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

//make priority queue
type Item struct {
	id       int
	priority int // this state is priority and distans from start
	index    int
}

type PriorityQueue []*Item

func (pq PriorityQueue) Len() int { return len(pq) }

// we want the ascending-priority-queue.
// So we use less than here.
func (pq PriorityQueue) Less(i, j int) bool {
	return pq[i].priority < pq[j].priority
}

func (pq PriorityQueue) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
	pq[i].index = j
	pq[j].index = i
}

func (pq *PriorityQueue) Push(x interface{}) {
	n := len(*pq)
	item := x.(*Item)
	item.index = n
	*pq = append(*pq, item)
}

func (pq *PriorityQueue) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	item.index = -1 //for safety
	*pq = old[0 : n-1]
	return item
}

func (pq *PriorityQueue) update(dist int, id int) {
	for _, i := range *pq {
		if i.id == id {
			if i.priority > dist {
				i.priority = dist
			}
		}
	}
}

// the main code
func nextInt(sc *bufio.Scanner) int {
	sc.Scan()
	n, _ := strconv.Atoi(sc.Text())
	return n
}

func dikstra(dist [][]int, n int) []int {
	// preparate priority queue
	inf := 1 << 30
	pq := make(PriorityQueue, n)
	shortests := make([]int, n)
	for i := 0; i < n; i++ {
		pq[i] = &Item{
			id:       i,
			priority: inf,
			index:    i,
		}

		shortests[i] = inf
	}
	pq[0].priority = 0
	shortests[0] = 0
	heap.Init(&pq)

	for pq.Len() > 0 {
		item := heap.Pop(&pq).(*Item)
		shortests[item.id] = item.priority
		for id, d := range dist[item.id] {
			if d != -1 {
				pq.update(item.priority+d, id)
			}
		}
		heap.Init(&pq)
	}
	return shortests
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	// init
	n := nextInt(sc)
	dist := make([][]int, n)
	for i := 0; i < n; i++ {
		dist[i] = make([]int, n)
		for j := 0; j < n; j++ {
			dist[i][j] = -1
		}
	}

	// std Input
	for i := 0; i < n; i++ {
		u := nextInt(sc)
		k := nextInt(sc)
		for j := 0; j < k; j++ {
			v, c := nextInt(sc), nextInt(sc)
			dist[u][v] = c
		}
	}

	shortests := dikstra(dist, n)
	for i, d := range shortests {
		fmt.Printf("%d %d\n", i, d)
	}
}

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();

  return 0;
}

C++: // #define _GLIBCXX_DEBUG // for STL debug (optional)
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <fstream>
#include <functional>
#include <bitset>
using namespace std;
using ll = long long int;
using int64 = long long int;
 
template<typename T> void chmax(T &a, T b) {a = max(a, b);}
template<typename T> void chmin(T &a, T b) {a = min(a, b);}
template<typename T> void chadd(T &a, T b) {a = a + b;}
 
int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};
const int INF = 1LL << 29;
const ll LONGINF = 1LL << 60;
const ll MOD = 1000000007LL;
 
int main() {
    int N; scanf("%d", &N);
    vector< vector< pair<int, int> > > G(N);
    for(int i=0; i<N; i++) {
        int u, k; scanf("%d%d", &u, &k);
        for(int j=0; j<k; j++) {
            int v, c; scanf("%d%d", &v, &c);
            G[u].emplace_back(v, c);
        }
    }

    vector<int> dist(N, INF), checked(N);
    dist[0] = 0, checked[0] = true;

    int u = 0;
    for(int i=0; i<N; i++) {
        for(auto e : G[u]) {
            int v, c; tie(v, c) = e;
            chmin(dist[v], dist[u] + c);
        }

        int ma = INF, v = 0;
        for(int k=0; k<N; k++) {
            if(checked[k]) continue;
            if(ma > dist[k]) {
                ma = dist[k];
                v = k;
            }
        }
        checked[v] = true;
        swap(u, v);
    }

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

C++: #include <iostream>
#include <algorithm>
#include <cmath>
#include <cstdio>
using namespace std;
#define MAX 10000000

int b[110];

int solve(int a[110][110], int n){
	b[0] = 0;
	for(int i = 0;i < n;i++){
		for(int j = 1;j < n;j++){
			//if(j == 4)cout << b[4] << i << " " << endl;
			if(a[i][j] != -1)b[j] = min(b[j], a[i][j]+b[i]);
			//if(j == 4)cout << b[4] << i << " " << endl;
		}
	}
	//cout << endl;
	return 0;
}

int main(){
	int a[110][110], n;
	fill((int*)a, (int*)(a+110), -1);
	fill(b, b+110, MAX);
	cin >> n;
	for(int i = 0;i < n;i++){
		int u, k, c, d;
		cin >> u >> k;
		for(int j = 0;j < k;j++){
			cin >> c >> d;
			a[u][c] = d;
		}
	}
	
	for(int i = 0;i < n;i++){
		for(int j = 0;j < n;j++){
			cout << a[i][j] << " ";
		}
		cout << endl;
	}
	
	for(int i = 0;i < 2*n;i++)solve(a, n);
	//solve(a, n);
	for(int i = 0;i < n;i++){
		cout << i << " " << b[i] << endl;
	}
	
	return 0;
}
/*
5
0 3 2 3 3 1 1 2
1 2 0 2 3 4
2 3 0 3 3 1 4 1
3 4 2 1 0 1 1 4 4 3
4 2 2 1 3 3
*/

C++: #include<stdio.h>
#define MAX 100
#define INF 999999
#define WHITE 0
#define BLACK 2

void dijkstra();

int n, G[MAX][MAX];

int main()
{
  int i, j, u, v, c, k;

  scanf("%d", &n);
  for(i=0; i<n; i++)
    {
      for(j=0; j<n; j++) G[i][j] = INF;
    }

  for(i=0; i<n; i++)
    {
      scanf("%d %d", &u, &k);
      for(j=0; j<k; j++)
	{
	  scanf("%d %d", &v, &c);
	  G[u][v] = c;
	}
    } 
  
  dijkstra();
  
  return 0;
}

void dijkstra()
{
  int d[n], color[n], i, u, v, mincost;

  for(i=0; i<n; i++)
    {
      d[i] = INF;
      color[i] = WHITE;
    }

  d[0] = 0;
  while(1)
    {
      mincost = INF;
      for(i=0; i<n; i++)
	{
	  if( d[i] < mincost && color[i] != BLACK )
	    {
	      mincost = d[i];
	      u = i;
	    }
	}

      if(mincost == INF)break;

      color[u] = BLACK;

      for(v=0; v<=n; v++)
	{
	  if(G[u][v] == INF) continue;

	  if(d[v] > d[u] + G[u][v]) 
	    {
	      d[v] = d[u] + G[u][v];
	    }
	}
    }
  
  for(i=0; i<n; i++)
    {
      printf("%d %d\n", i, d[i]);
    }
}

C++: #define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) REP(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define MSG(a) cout << #a << " " << a << endl;
#define REP(i, x, n) for (int i = x; i < n; i++)
#define OP(m) cout << m << endl
typedef long long ll;
typedef unsigned long long ull;

int main()
{
    int n;
    cin >> n;
    int m[n][n];
    rep(i, n) rep(j, n) m[i][j] = (i == j ? 0 : 1e8);
    rep(i, n)
    {
        int u, k;
        cin >> u >> k;
        rep(i, k)
        {
            int v, c;
            cin >> v >> c;
            m[u][v] = c;
        }
    }

    rep(k, n) rep(i, n) rep(j, n) m[i][j] = min(m[i][j], m[i][k] + m[k][j]);

    rep(i, n) cout << i << " " << m[0][i] << endl;

    return 0;
}