Go: // ダイクストラのアルゴリズム
package main

import (
	"bufio"
	"fmt"
	"log"
	"math"
	"os"
	"strconv"
	"strings"
)

type color int

const (
	white color = iota // 未訪問
	mst                // MSTとして確定
)

// 頂点
type node struct {
	num       int         // 頂点の番号
	weights   map[int]int // 重みMAP
	parent    *node       // MSTへの重み最小の親
	distFromS int         // 始点からの距離
	color     color
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	n := eGetInt(scanner)

	nodes := make([]*node, n)
	for i := 0; i < n; i++ {
		weights := eAtoi((strings.Fields(eGetline(scanner))))
		v := &node{weights[0], make(map[int]int, weights[1]), nil, math.MaxInt32, white}
		for j := 0; j < weights[1]; j++ {
			k := weights[j*2+2] // 相手の頂点名
			w := weights[j*2+3] // 重み
			v.weights[k] = w
		}
		nodes[i] = v
	}

	// 初回はnode[0]がMSTに入るように
	nodes[0].distFromS = 0

	for { // 全部チェックするまで

		// どの頂点を新たにMSTに取り込むか

		var minNode *node
		min := math.MaxInt32
		for _, v := range nodes {
			if v.color == mst {
				continue
			}
			if v.distFromS < min {
				min = v.distFromS
				minNode = v
			}
		}
		if minNode == nil {
			// すべて完了している.
			break
		}

		// MSTに追加する頂点決定
		minNode.color = mst

		// fmt.Printf(">[%v]\n", minNode)
		// MSTに属していない頂点それぞれについて,Startからの最小の重みの距離を更新
		for i, v := range nodes {
			if v.color == mst {
				continue
			}
			w, ok := minNode.weights[i]
			if !ok {
				// minNodeと接してない
				continue
			}

			if minNode.distFromS+w < v.distFromS {
				// minNode経由の距離がもっとも重みが少ないので親を変更
				v.distFromS = minNode.distFromS + w
				v.parent = minNode
				// fmt.Printf("[%v %v]\n", v, minNode)
			}
		}
		// fmt.Printf("<\n")
	}

	for i, v := range nodes {
		fmt.Printf("%d %d\n", i, v.distFromS)
	}
}

func eGetInt(scanner *bufio.Scanner) int {
	t := eAtoi(strings.Fields(eGetline(scanner)))
	return t[0]
}

func eGetline(p *bufio.Scanner) string {
	if !p.Scan() {
		if err := p.Err(); err != nil {
			log.Fatal(err.Error())
		}
		return ""
	}
	return p.Text()
}

func eAtoi(s []string) []int {
	ints := make([]int, len(s))
	var err error
	for i, e := range s {
		ints[i], err = strconv.Atoi(e)
		if err != nil {
			log.Fatal(err.Error())
		}
	}
	return ints
}

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;
}