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 <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define WHITE 0
#define VISITED 1
#define CANDIDATE 2

int dks(vvi &a, vi &d, vi &s, vi &p) {
  int total = 0, n = (int)a.size();
  while (true) {
    int min_cost = INT_MAX, u;
    rep(i, n) {
      if (s[i] != VISITED && d[i] < min_cost) {
        min_cost = d[i];
        u = i;
      }
    }

    if (min_cost == INT_MAX) break;

    s[u] = VISITED;
    if (p[u] != -1) total += a[p[u]][u];

    rep(v, n) {
      if (s[v] != VISITED && a[u][v] != -1) {
        if (d[u] + a[u][v] < d[v]) {
          d[v] = d[u] + a[u][v];
          p[v] = u;
          s[v] = CANDIDATE;
        }
      }
    }
  }
  
  return total;
}

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

  vvi g(n, vi(n, -1));
  rep(i, n) {
    int u, k;
    cin >> u >> k;

    rep(j, k) {
      int v, c;
      cin >> v >> c;

      g[u][v] = c;
    }
  }
  
  vi d(n, INT_MAX), s(n, WHITE), p(n, -1);
  d[0] = 0;
  
  dks(g, d, s, p);
  
  rep(i, n) printf("%d %d\n", i, d[i]);
}

C++: #include <iostream>
using namespace std;
static const int MAX = 100;
static const int INFTY = (1<<21);
static const int WHITH = 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] = WHITH;
  }

  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++: #include<iostream>
using namespace std;
static const int N = 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[N][N],d[N];

void dijkstra(int s){
	int color[N],p[N];
	for(int i=0;i<n;i++){
		color[i] = WHITE;
		d[i] = INFTY;
	}
	d[s] = 0;
	p[s] = -1;

	int u;
	while(1){
		int minv = INFTY;
		for(int i=0;i<n;i++){
			if(color[i]!=BLACK&&d[i]!=INFTY){
				if(d[i] < minv){
					minv = d[i];
					u = i;
				}
			}
		}
		if(minv == INFTY)break;
		color[u] = BLACK;
		for(int i=0;i<n;i++){
			if(color[i]!=BLACK&&M[u][i]!=INFTY){
				if(d[u]+M[u][i] < d[i]){
					d[i] = d[u]+M[u][i];
					p[i] = u;
				}
			}
		}
	}
}

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

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++: #include <iostream>
#include <cmath>
#include <vector>
#include <set>
#include <string>
#include <algorithm>

constexpr int INF = 10000001;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);
    int n, u, k, vv, cc;
    std::cin >> n;
    std::vector<std::vector<int>> v(n), c(n);
    std::vector<int> d(n), p(n);
    std::set<int> v_s, s;
    for (int i=0; i<n; i++) {
        std::cin >> u >> k;
        for (int j=0; j<k; j++) {
            std::cin >> vv >> cc;
            v[u].push_back(vv);
            c[u].push_back(cc);
        }
        d[i] = INF;
        v_s.insert(i);
    }
    d[0] = 0;
    //v_s.erase(0);

    while (not v_s.empty()) {
        int mind=INF+1;
        int minnode;
        auto iter = v_s.begin();
        for (int i=0; i<v_s.size(); i++,iter++) {
            if (d[*iter] < mind) {
                mind = d[*iter];
                minnode = *iter;
            }
        }
        v_s.erase(minnode);
        s.insert(minnode);
        for (int i=0; i<v[minnode].size(); i++) {
            if (v_s.find(v[minnode][i]) != v_s.end() and mind + c[minnode][i] < d[v[minnode][i]]) {
                d[v[minnode][i]] = mind + c[minnode][i];
                p[v[minnode][i]] = minnode;
            }
        }
    }

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

    return 0;
}