Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)

	g := makeGraph(n)
	for i := 0; i < n; i++ {
		u := getNextInt(scanner)
		k := getNextInt(scanner)
		for ii := 0; ii < k; ii++ {
			v := getNextInt(scanner)
			c := getNextInt(scanner)
			g[u][v] = c
		}
	}

	ans := make([]int, n)
	im := make(IntMap, 1)
	im.increment(0)
	for len(im) < n {
		min := 1 << 30
		x := -1
		for u := range im {
			for v := 0; v < n; v++ {
				if im.get(v) != 0 {
					continue
				}
				if min > ans[u]+g[u][v] {
					min = ans[u] + g[u][v]
					x = v
				}
			}
		}
		im.increment(x)
		ans[x] = min
	}

	for i := 0; i < n; i++ {
		fmt.Fprintln(writer, fmt.Sprintf("%d %d", i, ans[i]))
	}
	writer.Flush()
}

func makeGraph(n int) [][]int {
	g := make([][]int, n)
	for i := 0; i < n; i++ {
		g[i] = make([]int, n)
		for ii := 0; ii < n; ii++ {
			g[i][ii] = 1 << 30
		}
	}

	return g
}

// IntMap ...
type IntMap map[int]int

func (m IntMap) get(key int) int {
	if _, ok := m[key]; ok {
		return m[key]
	}
	return 0
}
func (m IntMap) increment(key int) {
	if _, ok := m[key]; ok == false {
		m[key] = 0
	}
	m[key]++
}

C++: #ifdef LOCAL_BUILD
#include "pch.h"
#define DLOG(msg) cout << "#" << __LINE__ << ":" << msg << endl;
#define DLOG_V(var) \
  cout << "#" << __LINE__ << ":" << #var << " : " << var << endl;
#else
#include <bits/stdc++.h>
#define DLOG(msg)
#define DLOG_V(var)
#endif
using namespace std;

int main() {
  int n;
  cin >> n;
  vector<vector<pair<int, int>>> edges(n, vector<pair<int, int>>());
  for (int i = 0; i < n; ++i) {
    int u, k;
    cin >> u >> k;
    for (int j = 0; j < k; ++j) {
      int v, c;
      cin >> v >> c;
      edges[i].push_back(make_pair(v, c));
    }
  }
  int count = 1;
  constexpr auto not_yet = numeric_limits<int>::max();
  vector<int> costs(n, not_yet);
  costs[0] = 0;
  auto cmp = [](const pair<int, int>& lhs, const pair<int, int>& rhs) {
    return lhs.second > rhs.second;
  };
  priority_queue<pair<int, int>, vector<pair<int, int>>, decltype(cmp)> q(cmp);
  for (auto&& edge : edges[0]) {
    q.push(edge);
  }
  while (true) {
    auto state = q.top();
    q.pop();
    if (costs[state.first] > state.second) {
      assert(costs[state.first] == not_yet);
      for (auto&& edge : edges[state.first]) {
        q.push(make_pair(edge.first, edge.second + state.second));
      }
      costs[state.first] = state.second;
      if (++count == n) {
        break;
      }
    }
  }
  for (int i = 0; i < n; ++i) {
    cout << i << " " << costs[i] << endl;
  }
}

C++: #include <iostream>
const int MAX_N = 100;
const int INF = 999999999;
const int WHITE = 0;
const int GRAY = 1;
const int BLACK = 2;
using namespace std;

int n;
int adj[MAX_N][MAX_N];
int color[MAX_N];
int d[MAX_N];

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

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

        color[u] = BLACK;
        for (int v = 0; v < n; v++) {
            if (color[v] != BLACK && adj[u][v] != INF) {
                if (d[v] > d[u] + adj[u][v]) {
                    d[v] = d[u] + adj[u][v];
                    color[v] = GRAY;
                }
            }
        }
    }
}

int main(void) {
    cin >> n;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++) adj[i][j] = INF;

    for (int i = 0; i < n; i++) {
        int u, k; cin >> u >> k;
        for (int j = 0; j < k; j++) {
            int v, c; cin >> v >> c;
            adj[u][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 color[MAX], d[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) {
  	      	  minv = d[i];
  	      	  u = i;
  	      }
      }
      if(u = -1) break;
      color[u] = BLACK;
      for(int v =  0; v < n; i++) {
      	  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;
	int u, k c;
	for(int i = 0; i < n; i++) {
		for(int j = 0; j < n; j++) {
			M[i][i] = INFTY;
		}
	}
	
	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 <queue>
#include <cstdio>
#include <vector>
using namespace std;
int V, s, t, p, q, d[100]; vector<pair<int, int> > G[100];
int main() {
	scanf("%d", &V);
	for(int i = 0; i < V; i++) {
		scanf("%d%d", &s, &t);
		for(int j = 0; j < t; j++) {
			scanf("%d%d", &p, &q);
			G[i].push_back(make_pair(p, q));
		}
	}
	for(int i = 1; i < V; i++) d[i] = 999999999;
	priority_queue<pair<int, int> > que; que.push(make_pair(0, 0));
	while(!que.empty()) {
		int v = que.top().second; que.pop();
		for(int i = 0; i < G[v].size(); i++) {
			int u = G[v][i].first, w = G[v][i].second;
			if(d[u] > d[v] + w) {
				d[u] = d[v] + w;
				que.push(make_pair(-d[u], u));
			}
		}
	}
	for(int i = 0; i < V; i++) printf("%d %d\n", i, d[i]);
	return 0;
}

C++: #include <cstdio>
static const int INFTY = (1 << 21);
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;

int n, **M;
int *d, *p;

void dijkstra() {
    int u, minv;
    int d[n], p[n], color[n];

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

    while (1) {
        u = -1;
        minv = INFTY;
        for (int i = 0; i < n; i++) {
            if (color[i] != BLACK && d[i] < minv) {
                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[u] + M[u][v] < d[v]) {
                    p[v] = u;
                    d[v] = d[u] + M[u][v];
                    color[v] = GRAY;
                }             
            }
        }
    }
    
    for (int i = 0; i < n; i++) {
        printf("%d %d\n", i, d[i]);
    }
}

int main() {
    scanf("%d", &n);

    M = new int*[n];
    for (int i = 0; i < n; i++) {
        M[i] = new int[n];
        for (int j = 0; j < n; j++) {
            M[i][j] = INFTY;
        }
    }

    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);
            M[u][v] = c;
        }
    }

    dijkstra();

    return 0;
}