Go: package main

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

func main() {
	r := bufio.NewReader(os.Stdin)

	var n int
	fmt.Fscan(r, &n)
	cs := make([]map[int]int, n) // []v_i -> c_i
	for h := 0; h < n; h++ {
		var u, k int
		fmt.Fscan(r, &u, &k)
		m := make(map[int]int)
		for i := 0; i < k; i++ {
			var v, c int
			fmt.Fscan(r, &v, &c)
			m[v] = c
		}

		cs[u] = m
	}

	q := make(map[int]int)
	q[0] = 0
	visited := make(map[int]struct{})
	out := make([]int, n)

	for len(q) > 0 {
		u := top(q)
		for uu, c := range cs[u] {
			// Consider the connection between u and uu.
			if _, ok := visited[uu]; ok {
				continue
			}
			if d, ok := q[uu]; !ok || d > q[u]+c {
				q[uu] = q[u] + c
			}
		}

		out[u] = q[u]
		delete(q, u)
		visited[u] = struct{}{}
	}

	for u, d := range out {
		fmt.Println(u, d)
	}
}

func top(q map[int]int) int {
	minu := -1
	min := -1
	for u, d := range q {
		if min < 0 || d < min {
			minu = u
			min = d
		}
	}

	return minu
}

C++: #ifdef LOCAL
#pragma GCC optimize ("O0")
#else
#pragma GCC optimize ("O3")
#endif


#include <bits/stdc++.h>


using namespace std;

using ll = long long;
const int INF = 1e9 + 7;
const int MOD = INF;
const ll INF_LL = 1e18 + 7;

#define __overload3(_1, _2, _3, name,...) name
#define rep(...) __overload3(__VA_ARGS__, repFromUntil, repUntil, repeat)(__VA_ARGS__)
#define repeat(times) repFromUntil(__name, 0, times)
#define repUntil(name, times) repFromUntil(name, 0, times)
#define repFromUntil(name, from, until) for (int name = from, name##__until = (until); name < name##__until; name++)
#define repFromTo(name, from, to) repFromUntil(name, from, to + 1)
#define repr(...) __overload3(__VA_ARGS__, reprFromUntil, reprUntil, repeat)(__VA_ARGS__)
#define reprUntil(name, times) reprFromUntil(name, 0, times)
#define reprFromUntil(name, from, until) for (int name = until - 1, name##__from = (from); name >= name##__from; name--)
#define reprFromTo(name, from, to) reprFromUntil(name, from, to + 1)

#define debugos OUT
#ifdef LOCAL
#define debug(v) {printf("L%d %s > ",__LINE__,#v);debugos<<(v)<<newl;}
#define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:(v)){debugos<<e<<" ";}debugos<<newl;}
#define debuga(m,w) {printf("L%d %s > ",__LINE__,#m);for(int x=0;x<(w);x++){debugos<<(m)[x]<<" ";}debugos<<newl;}
#define debugaa(m,h,w) {printf("L%d %s >\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){debugos<<(m)[y][x]<<" ";}debugos<<newl;}}
#else
#define debug(v) {}
#define debugv(v) {}
#define debuga(m,w) {}
#define debugaa(m,h,w) {}
#endif

#define newl "\n"

#define all(iter) begin(iter), end(iter)


template <class T> bool chmin(T& var, T x) {
  if (var > x) {
    var = x;
    return true;
  } else return false;
}
template <class T> bool chmax(T& var, T x) {
  if (var < x) {
    var = x;
    return true;
  } else return false;
}

class MyScanner {
  public:
    template<typename T> void input_integer(T& var) {
        var = 0; T sign = 1;
        int cc = getchar();
        for (; cc<'0' || '9'<cc; cc = getchar())
            if (cc == '-') sign = -1;
        for (; '0' <= cc && cc <= '9'; cc = getchar())
            var = (var << 3) + (var << 1) + cc - '0';
        var = var * sign;
    }
    int c() { char c; while (c = getchar(), c == ' ' or c == '\n'); return c; }
    MyScanner& operator>>(char& var) { var = c(); return *this; }
    MyScanner& operator>>(int& var) { input_integer<int>(var); return *this; }
    MyScanner& operator>>(ll& var) { input_integer<ll>(var); return *this; }
    MyScanner& operator>>(string& var) {
        int cc = getchar();
        for (; !isvisiblechar(cc); cc = getchar());
        for (; isvisiblechar(cc); cc = getchar())
            var.push_back(cc);
        return *this;
    }
    operator int() {
      int n;
      *this >> n;
      return n;
    }
    operator ll() {
      ll n;
      *this >> n;
      return n;
    }
    private:
      int isvisiblechar(int c) {
        return 0x21 <= c && c <= 0x7E;
      }
};
class MyPrinter {
  public:
    template<typename T>
    void output_integer(T var) {
        if (var == 0) { putchar('0'); return; }
        if (var < 0)
            putchar('-'),
            var = -var;
        char stack[32]; int stack_p = 0;
        while (var)
            stack[stack_p++] = '0' + (var % 10),
            var /= 10;
        while (stack_p)
            putchar(stack[--stack_p]);
    }
    MyPrinter& operator<<(char c) { putchar(c); return *this; }
    template <typename T>
    MyPrinter& operator<<(T var) { output_integer<T>(var); return *this; }
    MyPrinter& operator<<(char* str_p) { while (*str_p) putchar(*(str_p++)); return *this; }
    MyPrinter& operator<<(const char* str_p) { while (*str_p) putchar(*(str_p++)); return *this; }
    MyPrinter& operator<<(const string& str) {
        const char* p = str.c_str();
        const char* l = p + str.size();
        while (p < l) putchar(*p++);
        return *this;
    }
    // MyPrinter& operator<<(const modint& var) { output_integer<ll>(var.value); return *this; }
    template <typename T>
    void operator()(T x) {
        *this << x << newl;
    }
};
MyScanner IN;
MyPrinter OUT;

class union_find {
  public:
    /// <param name="len">要素数</param>
    union_find(int len) {
      parents = new int[len];
      depths = new int[len];
      for (int i = 0; i < len; i++) parents[i] = i;
      memset(depths, 0, len);
    }
    /// 根を特定　あまり外部から使わない
    int root(int x) {
      return parents[x] == x ? x :
             root(parents[x]);
    }
    /// 2つの要素が同じ木に属すると宣言
    void unite(int x, int y) {
      x = root(x);
      y = root(y);
      if (x == y) return;
      if (depths[x] < depths[y]) parents[x] = y;
      else {
        parents[y] = x;
        if (depths[x] == depths[y]) depths[x]++;
      }
    }
    /// 同じ木に属するか
    bool same(int x, int y) {
      return root(x) == root(y);
    }
  private:
    int *parents;
    int *depths;
};

struct edge {
  int to, cost;
};

int main() {
  int n = IN;
  vector<edge> graph[n];
  rep(i, n) {
    int u = IN, k = IN;
    rep(k) {
      int v = IN, c = IN;
      graph[u].push_back({v, c});
    }
  }

  vector<int> res(n, INF);
  using P = pair<int, int>;
  queue<P> q;
  q.push({0, 0});

  while (!q.empty()) {
    P p = q.front(); q.pop();
    int v = p.first, d = p.second;
    if (d < res[v]) {
      res[v] = d;
      for (auto&& e : graph[v]) q.push({e.to, d + e.cost});
    }
  }

  rep(i, n) OUT << i << " " << res[i] << newl;
}

C++: #include<iostream>
using namespace std;

static const int MAX =100;
static const int INFTY = (1<<21);
static const int black= 2;
static const int gray= 1;
static const int white= 0;

int n,M[MAX][MAX];

void d()
{
  int i,u,j,minv;
  int d[MAX],iro[MAX];

  for(i=0;i<n;i++)
    {
      d[i] = INFTY;
      iro[i] = white;
    }

  d[0] = 0;
  iro[0] = gray;
  while(1)
    {
      minv = INFTY;
      u = -1;
      for(i=0;i<n;i++)
	{
	  if(minv > d[i] && iro[i] != black)
	    {
	      u = i;
	      minv = d[i];
	    }
	}
      if(u==-1) break;
      iro[u] = black;
      for(j=0;j<n;j++)
	{
	  if(iro[j] != black && M[u][j] != INFTY)
	    {
	      if( d[j] > d[u] + M[u][j])
		{
		  d[j] = d[u] + M[u][j];
		  iro[j] = 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 p = 0; p < n; p++)
	{
	  M[i][p] = INFTY;
	}
    }

  int k,c,u,v;
  for(int i =0 ; i < n ; i++)
    {
      cin >> u >> k;
      for(int p = 0; p < k; p++)
	{
	  cin >> v >> c;
	  M[u][v] = c;
	}
    }
  d();

  return 0;
}