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++: #include <bits/stdc++.h>
using namespace std;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
#define P(x) cout << (x) << endl
#define p(x) cout << (x)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define vv(type, c, m, n, i) vector<vector<type>> c(m, vector<type>(n, i));
#define rep(i,a,n) for(int i=(a), i##_len=(n); i<i##_len; ++i)
#define rrep(i,a,n) for(int i=(a), i##_len=(n); i>i##_len; --i)
#define len(x) ((int)(x).size())
#define mp make_pair
#define eb emplace_back
typedef long long ll;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<long long> vll;
typedef vector<string> vs;
typedef vector<bool> vb;
constexpr int MAX = 100;
enum Color { WHITE = 0, GRAY, BLACK };
int n;
vv(int, M, MAX, MAX, INT_MAX);
inline void dijkstra() {
    vi d(MAX, INT_MAX), color(MAX, WHITE);
    d[0] = 0;
    color[0] = GRAY;
    int minv, u;
    while(true) {
        minv = INT_MAX;
        u = -1;
        rep(i, 0, n) {
            if(minv > d[i] && color[i] != BLACK) {
                u = i;
                minv = d[i];
            }
        }
        if(u == -1) break;
        color[u] = BLACK;
        rep(v, 0, n) {
            if(color[v] != BLACK && M[u][v] != INT_MAX && d[v] > d[u] + M[u][v]) {
                d[v] = d[u] + M[u][v];
                color[v] = GRAY;
            }
        }
    }
    rep(i, 0, n) {
        cout << i << " " << d[i] << "\n";
    }
}
int main() {
    cin >> n;
    int u, k, v, c;
    rep(i, 0, n) {
        cin >> u >> k;
        rep(j, 0, k) {
            cin >> v >> c;
            M[u][v] = c;
        }
    }
    dijkstra();
    return 0;
}

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

int n;
vector<pair<int, int>> adj[100];
int *d;

void dijkstra() {
    priority_queue<pair<int, int>> PQ;
    int d[n], color[n];

    for (int i = 0; i < n; i++) {
        d[i] = INFTY;
        color[n] = WHITE;
    }
    d[0] = 0;
    PQ.push(make_pair(0, 0));

    while (!PQ.empty()) {
        pair<int, int> f = PQ.top();
        PQ.pop();

        int u = f.second;
        color[u] = BLACK;

        if (d[u] < f.first * (-1)) { continue; }

        for (int j = 0; j < adj[u].size(); j++) {
            int v = adj[u][j].first;
            if (color[v] == BLACK) { continue; }
            if (d[u] + adj[u][j].second < d[v]) {
                d[v] = d[u] + adj[u][j].second;
                // printf("d[%d] = %d\n", v, d[v]);
                PQ.push(make_pair(d[v] * (-1), v));
                color[v] = GRAY;
            }
        }
    }
    
    for (int i = 0; i < n; i++) {
        printf("%d %d \n", i, d[i]);
    }
}

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

    // adj = new vector<pair<int, int>>[n];

    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);
            adj[u].push_back(make_pair(v, c));
        }
    }

    dijkstra();

    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 GRRAY = 1;
static const int BLACK = 2;

int n;
int M[100][100];

int dijkstra(){
  int u,minv,i,v;
  int d[MAX],color[MAX];

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

  d[0]=0;
  color[0]=GRRAY;
  while(1){
    minv=INFTY;
    u=-1;
    for(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(v=0;v<n;v++){
      if(M[u][v] != INFTY && color[v] != BLACK){
	if(d[v]>d[u]+M[u][v]){
	  d[v]=d[u]+M[u][v];
	  color[v]=GRRAY;
	}
      }
    }
  }
    for(i=0;i<n;i++){
      cout << i << " " << (d[i] == INFTY ? -1 : d[i]) << endl;
    }
}

int main(){
  int i,j;

  cin >> n;
 
 for(i=0;i<n;i++){
    for(j=0;j<n;j++){
      M[i][j]=INFTY;
    }
  }

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

C++: #include <iostream>
#include<cstdio>
#include <algorithm>
using namespace std;
typedef long long ll;
ll dp[105][105];
const ll INF = 0x3f3f3f3f;
int main()
{
    int n,i,m,j,a,b,k;
    scanf("%d",&n);
    for(i = 0;i < n;i++)
        for(j = 0;j < n;j++)
            dp[i][j] = INF;
    dp[0][0] = 0;
    for(j = 0;j < n;j++)
    {
        cin >> i >> m;
        while(m--)
        {
            cin >> a ;
            cin >> dp[i][a];
        }
    }
    for(k = 0;k < n;k++)
        for(i = 0;i < n;i++)
            for(j = 0;j < n;j++)
                dp[i][j] = min(dp[i][j],dp[i][k]+dp[k][j]);
    for(i = 0;i < n;i++)
        cout << i << ' ' << dp[0][i] << endl;
    return 0;
}

C++: #include<bits/stdc++.h>
#define ll long long
#define rep(i, n) for(int i=0;i<(n);++i)
#define per(i, n) for(int i=(n)-1;i>=0;--i)
#define repa(i, n) for(int i=1;i<(n);++i)
#define foreach(i, n) for(auto &i:(n))
#define pii pair<int, int>
#define pll pair<long long, long long>
#define all(x) (x).begin(), (x).end()
#define bit(x) (1ll << (x))
const ll MOD = (ll)1e9+7;
const int INF = (ll)1e9+7;
const ll INFLL = (ll)1e18;
using namespace std;
template<class t>
using vvector = vector<vector<t>>;
template<class t>
using vvvector = vector<vector<vector<t>>>;
template<class t>
using priority_queuer = priority_queue<t, vector<t>, greater<t>>;
template<class t, class u> bool chmax(t &a, u b){if(a<b){a=b;return true;}return false;}
template<class t, class u> bool chmin(t &a, u b){if(a>b){a=b;return true;}return false;}

ll modpow(ll x, ll b){
	ll res = 1;
	while(b){
		if(b&1)res = res * x % MOD;
		x = x * x % MOD;
		b>>=1;
	}
	return res;
}

ll modinv(ll x){
	return modpow(x, MOD-2);
}

bool was_output = false;
template<class t>
void output(t a){
	if(was_output)cout << " ";
	cout << a;
	was_output = true;
}
void outendl(){
	was_output = false;
	cout << endl;
}

class dijkstra{
public:
	int n;
	vvector<pll> edges;
	vector<ll> fast;
	dijkstra(int N):n(N){
		edges.resize(n);
	}

	void add_edge(int from, int to, ll cost){
		edges[from].emplace_back(to, cost);
	}

	void solve(int start){
		priority_queuer<pll> pq;
		fast.assign(n, INFLL);
		pq.emplace(0, 0);
		fast[start] = 0;
		pq.emplace(0, start);
		while(pq.size()){
			pll d = pq.top();
			pq.pop();
			if(d.first!=fast[d.second])continue;
			foreach(i, edges[d.second]){
				ll next_time = d.first + i.second;
				int to = i.first;
				if(fast[to] <= next_time)continue;
				fast[to] = next_time;
				pq.emplace(next_time, to);
			}
		}
	}
};


int main(){
	int n;
	cin >> n;
	dijkstra dij(n);
	rep(i, n){
		int from;
		cin >> from;
		int time;
		cin >> time;
		rep(j, time){
			int to;
			ll cost;
			cin >> to >> cost;
			dij.add_edge(from, to, cost);
		}
	}
	dij.solve(0);
	rep(i, n){
		output(i);
		output(dij.fast[i]);
		outendl();
	}
	return 0;
}