Go: package main

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

var sc = bufio.NewScanner(os.Stdin)

const T = 10000000

var n int
var A [101][101]int

func nextInt() int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return i
}
func Shortestsearch() {
	var Minimum int
	var d, color [100]int
	var u int

	for i := 0; i < n; i++ {
		d[i] = T
		color[i] = 0
	}

	d[0] = 0
	color[0] = 1

	for {
		Minimum = T
		u = -1
		for i := 0; i < n; i++ {
			if Minimum > d[i] && color[i] != 2 {
				u = i
				Minimum = d[i]
			}
		}
		if u == -1 {
			break
		}
		color[u] = 2
		for j := 0; j < n; j++ {
			if color[j] != 2 && A[u][j] != T {
				if d[j] > d[u]+A[u][j] {
					d[j] = d[u] + A[u][j]
					color[j] = 1
				}
			}
		}
	}
	for i := 0; i < n; i++ {
		fmt.Printf("%d %d\n", i, d[i])
	}
}
func main() {
	sc.Split(bufio.ScanWords)
	n = nextInt()

	for i := 0; i < n; i++ {
		for j := 0; j < n; j++ {
			A[i][j] = T
		}
	}
	for i := 0; i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			v := nextInt()
			c := nextInt()
			A[u][v] = c
		}
	}
	Shortestsearch()
}

C++: #include <iostream>

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)

constexpr int MAXN = 100;
constexpr int MAXINT = 100001;


int G[MAXN][MAXN];
int D[MAXN];
int C[MAXN];
int P[MAXN];
int n;

int main() {
    std::cin >> n;
    FOR(i, 0, n)
    FOR(j, 0, n)
    {
        G[i][j] = MAXINT;
    }

    FOR(i, 0, n){
        int id, e;
        std::cin >> id >> e;
        FOR(i, 0, e) {
            int v, c;
            std::cin >> v >> c;
            G[id][v] = c;
        }
    }

    FOR(i, 0, n) D[i] = MAXINT;

    int r = -1;
    D[0] = 0;
    while (true) {
        int mincost = MAXINT;
        int t;
        for (int i = 0; i < n; i++) {
            if ((C[i] == 0)  && (D[i] < mincost)) {
                mincost = D[i];
                t = i;
            }
        }

        if (mincost == MAXINT) {
            break;
        }

        C[t] = 1;
        P[t] = r;

        for (int i = 0; i < n; i++) {
            if ((C[i] == 0) && ((D[t] + G[t][i]) < D[i])) {
                D[i] = D[t] + G[t][i];
            }
        }
        r = t;
    }
    FOR(i, 0, n) {
        std::cout << i << " " << D[i] << std::endl;
    }
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<queue>
#include<vector>
#include<stack>
using namespace std;
#define MAX 100
#define WHITE 0
#define GRAY 1
#define BLACK 2
#define INFTY (1<<30)
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<bits/stdc++.h>
using namespace std;
using ll = long long;

// #undef DEBUG
#define DEBUG
/// {{{ DEBUG --- ///
#ifdef DEBUG
template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) { o << "{"; for(size_t i = 0; i < v.size(); i++) o << v[i] << (i + 1 != v.size() ? ", " : ""); o << "}"; return o; }
#ifdef USE_COUT
#define dump(...) [&](){auto __debug_tap=make_tuple(__VA_ARGS__);cout<<"["<<__LINE__<< "] "<<#__VA_ARGS__<<" = "<<__debug_tap<<"\n";}()
#else
#define dump(...) [&](){auto __debug_tap=make_tuple(__VA_ARGS__);cerr<<"["<<__LINE__<< "] "<<#__VA_ARGS__<<" = "<<__debug_tap<<"\n";}()
#endif
template<class T> inline void dump2D(T &d, size_t sizey, size_t sizex) { ostream&o=
#ifdef USE_COUT
  cout;
#else
  cerr;
#endif
  for(size_t i = 0; i < sizey; i++) { for(size_t j = 0; j < sizex; j++) o << d[i][j] << " "; o << endl; }
}
#else
template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) { for(size_t i = 0; i < v.size(); i++) o << v[i] << (i + 1 != v.size() ? " " : ""); return o; }
#define dump(...) (42)
#define dump2D(...) (42)
#endif
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream &, tuple<T...> const &){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream & os, tuple<T...> const & t){ os << (n==0?"":", ") << get<n>(t); _ot<n+1>(os, t); }
template<class...T> ostream & operator<<(ostream &o, tuple<T...> const &t){ o << "("; _ot<0>(o, t); o << ")"; return o; }
template<class T, class U> ostream & operator<<(ostream &o, pair<T, U> const &p) { o << "(" << p.first << ", " << p.second << ")"; return o; }
/// }}}--- ///

template<class T = int, class U = uint64_t>
struct RadixHeap {
private:
  std::vector< pair<U, T> > v[sizeof(U) * 8 + 1];
  std::size_t sz = 0;
  U last = 0;
  std::size_t logbinll(U x) {
    std::size_t h = 0;
    x = x & 0xFFFFFFFF00000000 ? (h += 32, x) & 0xFFFFFFFF00000000 : x;
    x = x & 0xFFFF0000FFFF0000 ? (h += 16, x) & 0xFFFF0000FFFF0000 : x;
    x = x & 0xFF00FF00FF00FF00 ? (h += 8, x) & 0xFF00FF00FF00FF00 : x;
    x = x & 0xF0F0F0F0F0F0F0F0 ? (h += 4, x) & 0xF0F0F0F0F0F0F0F0 : x;
    x = x & 0xCCCCCCCCCCCCCCCC ? (h += 2, x) & 0xCCCCCCCCCCCCCCCC : x;
    x = x & 0xAAAAAAAAAAAAAAAA ? (h += 1, x) & 0xAAAAAAAAAAAAAAAA : x;
    return h;
  }
public:
  void push(U x, T y) {
    // assert(last <= f(x));
    v[logbinll(x^last)].emplace_back(x, y);
    sz++;
  }
  pair<U, T> pop() {
    // assert(sz);
    if(!v[0].size()) {
      std::size_t i = 1;
      while(!v[i].size()) i++;
      last = min_element(begin(v[i]), end(v[i]))->first;
      for(const pair<U, T> & e : v[i])
        v[logbinll(e.first ^ last)].emplace_back(e);
      v[i].clear();
    }
    sz--;
    pair<U, T> res = v[0].back();
    v[0].pop_back();
    return res;
  }
  std::size_t size() { return sz; }
};

vector<pair<int, int>> g[100];
int n;
int main() {
  std::ios::sync_with_stdio(false), std::cin.tie(0);
  cin >> n;
  for(int i = 0; i < n; i++) {
    int x, m;
    cin >> x >> m;
    while(m--) {
      int t, c;
      cin >> t >> c;
      g[x].emplace_back(t, c);
    }
  }
  // dijkstra {{{
  vector<ll> dist(n, 1e18);
  RadixHeap<int> rh;
  rh.push(0, 0);
  dist[0] = 0;
  while(rh.size()) {
    ll di; int i;
    tie(di, i) = rh.pop();
    if(dist[i] < di) continue;
    for(auto to : g[i]) {
      int j = to.first;
      ll ndi = di + to.second;
      if(dist[j] > ndi) {
        dist[j] = ndi;
        rh.push(ndi, j);
      }
    }
  }
  // }}}
  for(int i = 0; i < n; i++)cout << i << " "<< dist[i] << endl;
  return 0;
}