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<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 min;
   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 ) {
      min = INFTY; 
      int a = -1;
      for ( int i = 0; i < n; i++ ) {
         if ( min > d[i] && color[i] != BLACK ) {
             a = i;
             min = d[i];
         }
      }
  
      if ( a == -1 ) break;
      color[a] = BLACK;
        
      for ( int v = 0; v < n; v++ ) {
         if ( color[v] != BLACK && M[a][v] != INFTY ) {
            if ( d[v] > d[a] + M[a][v] ) {
               d[v] = d[a] + M[a][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, a, v;
    
   for ( int i = 0; i < n; i++ ) {
      cin >> a >> k;  
  
      for ( int j = 0; j < k; j++ ) {
         cin >> v >> c;
         M[a][v] = c;
      }
   }
  
   dijkstra();
  
   return 0;
}

C++: #include <cstdio>
#include <cctype>
#include <climits>
#include <vector>
#include <queue>
using namespace std;

#define si static inline
#define gcu getchar_unlocked
si int in() {
	int c, n = 0;
	bool minus = false;
	if ((c = gcu()) == '-') minus = true; else ungetc(c, stdin);
	while ((c = gcu()) >= '0' && c <= '9') n = 10 * n + (c - '0');
	//return n; }
	return minus ? -n : n; }
si void scan(char *s) {while (!isspace(*s++ = gcu()));}
#define pcu putchar_unlocked
#define svo si void out
template <typename T>
svo(T n) {
	static char buf[20];
	char *p = buf;
	//if(n < 0) pcu('-'), n *= -1;
	if (!n) *p++ = '0';
	else while (n) *p++ = n % 10 + '0', n /= 10;
	while (p != buf) pcu(*--p); }
svo(const char *s){while(*s)pcu(*s++);}
svo(char *s){while(*s)pcu(*s++);}
svo(char c){pcu(c);}
template <typename T>
//svo(vector<T> &v){for(T &x:v)out(' '),out(x);out('\n');}
svo(vector<T> &v){for(T &x:v)out(&x == &v[0]?"":" "),out(x);out('\n');}
template <typename head, typename... tail>
svo(head&& h, tail&&... t){out(h);out(move(t)...);}
#undef svo
#undef si

#define v vector
struct graph {
	struct node {int n, w;};
	v<v<node>> nodes;

	void read(int n) {
		nodes.resize(n);
		for (auto &x: nodes) {
			in();
			for (int k = in(); k--;) {
				int c = in();
				x.push_back({c, in()});
			}
		}
	}

	v<node> dks() {
		v<node> w(nodes.size(), {0, INT_MAX});
		w[0].w = 0;
		priority_queue<node> q;
		q.push({0, 0});
		while (!q.empty()) {
			node n = q.top();
			q.pop();
			if (w[n.n].n)
				continue;
			w[n.n].n = 1;
			for (node &x: nodes[n.n]) {
				w[x.n].w = min(w[x.n].w, n.w + x.w);
				q.push({x.n, w[x.n].w});
			}
		}
		return move(w);
	}
};

bool operator < (const graph::node &a, const graph::node &b) {
	return a.w > b.w;
}

int main() {
	graph g;
	g.read(in());
	int i = 0;
	for (auto &x: g.dks())
		out(i++, ' ', x.w, '\n');
}

C++: #include <iostream>
#include <cstdlib>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <set>
#include <string>
#include <cmath>
using namespace std;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define REP(i, k, n) for (int i = (int)(k); i < (int)(n); i++)
#define rrep(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rREP(i, k, n) for (int i = (int)(n)-1; i >= k; i--)

#define debug(x) cerr<<#x<<": "<<x<<'\n'

#define fi first
#define se second

#define vi vector<int>
#define pb push_back
#define mp make_pair

#define pcnt __builtin_popcount

typedef long long ll;

const int inf = 100100100;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;

struct Edge{
    int to;
    int cost;
};
vector<vector<Edge> > G(110);
int d[110] = {};
int main(){
    int n;
    cin >> n;
    rep(i,n){
        int t,m;
        cin >> t >> m;
        rep(j,m){
            int a,b;
            cin >> a >> b;
            Edge ee;
            ee.to = a;ee.cost = b;
            G[t].push_back(ee);
        }
    }

    rep(i,n) d[i] = 900010000;
    d[0] = 0;
    while(true){
        bool update = false;
        rep(i,n){
            for(const auto& e: G[i]){
                if(d[i] + e.cost < d[e.to]){
                    d[e.to] = d[i]+e.cost;
                    update = true;
                }
            }
        }
        if(!update) break;
    }

    rep(i,n){
        cout << i << " " << d[i] << endl;
    }

    return 0;
}

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

struct edge { int from, to, cost; };
const int MAX_V=100;
const int INF=1e9;

vector<edge> es;
int d[MAX_V];
int n;

void shortest_path(int s){
  REP(i, n) d[i] = INF;
  d[s] = 0;
  while(true){
    bool update = false;
    for(edge e : es){
      if(d[e.from] != INF && d[e.to] > d[e.from] + e.cost){
	d[e.to] = d[e.from] + e.cost;
	update = true;
      }
    }
    if(!update) break;
  }
}

int main(){
  cin>>n;
  REP(i,n){
    int u, k; cin>>u>>k;
    REP(j,k){
      edge e;
      e.from = u;
      cin>>e.to>>e.cost;
      es.push_back(e);
    }
  }
  shortest_path(0);
  REP(i,n){
    cout<<i<<" "<<d[i]<<endl;
  }
}