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 <cstdio>
#include <map>
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;
map<int, int> *M;
int *d;

void dijkstra() {
    int u, minv;
    int d[n], color[n];

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

    while (1) {
        u = -1;
        minv = INFTY;
        for (int i = 0; i < n; i++) {
            if (color[i] != BLACK && d[i] < minv) {
                u = i;
                minv = d[i];
            }
        }

        if (u == -1) { break; }

        color[u] = BLACK;
        for (map<int, int>::iterator it = M[u].begin(); it != M[u].end(); it++) {
            if (color[it->first] != BLACK) {
                if (d[u] + it->second < d[it->first]) {
                    d[it->first] = d[u] + it->second;
                    color[it->first] = GRAY;
                }
            }
        }
    }
    
    for (int i = 0; i < n; i++) {
        printf("%d %d\n", i, d[i]);
    }
}

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

    M = new map<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);
            M[u][v] = c;
        }
    }

    dijkstra();

    return 0;
}

C++: #include <iostream>
#include <vector>
#include <string>
#include <bitset>
#include <cmath>
#include <queue>
#include <iomanip>
#include <algorithm>
#include <stack>
#include <cmath>
using namespace std;

#define INF 1e18
#define int long long
static const int MAX = 110;
static const int NOTFIXED = 0;
static const int FIXED = 1;

int n, m[MAX][MAX];

void dijkstra() {
    int d[n], status[n];
    for(int i = 0; i < n; i++) {
        d[i] = INF;
        status[i] = NOTFIXED;
    }
    d[0] = 0;
    status[0] = NOTFIXED;

    while(true) {
        int u = -1;
        int minv = INF;
        for(int i = 0; i < n; i++) {
            if(minv > d[i] && status[i] != FIXED) {
                u = i;
                minv = d[i];
            }
        }

        if(u == -1) break;
        status[u] = FIXED;
        for(int v = 0; v < n; v++) {
            if(m[u][v] != INF && status[v] != FIXED) {
                if(d[v] > d[u] + m[u][v]) {
                    d[v] = d[u] + m[u][v];
                    status[v] = NOTFIXED;
                }
            }
        }
    }

    for(int i = 0; i < n; i++) {
        cout << i << " " << (d[i] == INF ? -1 : d[i]) << endl;
    }
}

signed main() {
    cin >> n;

    for(int i = 0; i < n; i++) {
        for(int j = 0; j < n; j++) {
            m[i][j] = INF;
        }
    }

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

    dijkstra();

    return 0;
}

C++: #include <iostream>
#include <cmath>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;
const int INF = 1e9 ;
const int MAXN = 10100 ;
vector<pair<int, int> > edge[MAXN];
int n;
int d[MAXN], vis[MAXN];
priority_queue<pair<int, int> > q;
void Dij()
{
	for (int i = 0; i < n; ++i) d[i] = INF;
	d[0] = 0;
	q.push(make_pair(0, 0)) ;
	vis[0] = 1;
	while (! q.empty())
	{
		pair<int, int> cur = q.top();
		int u = cur.second;
		q.pop();
		vis[u] = 2;
		if (d[u] < cur.first * (-1)) continue ;
		for (int i = 0; i < edge[u].size(); ++i)
		{
			int to = edge[u][i].first;
			if (vis[to] == 2) continue ;
			if (d[to] > d[u] + edge[u][i].second)
			{
				d[to] = d[u] + edge[u][i].second;
				q.push(make_pair(d[to] * (-1), to));
				vis[to] = 1;
			}
		}
	}
}
int main()
{
	cin >> n;
	for (int i = 1; i <= n; ++i)
	{
		int u, k;
		cin >> u >> k;
		for (int j = 1; j <= k; ++j)
		{
			int v, c;
			cin >> v >> c;
			edge[u].push_back(make_pair(v, c));
		}
	}
	Dij();
	for (int i = 0; i < n; ++i)
		cout << i << " " << (d[i] == INF ? -1 : d[i]) << endl;
	return 0;
}

C++: #include<iostream>
#include<queue>
#define INF 100000000
using namespace std;
int main(){
  int n;cin>>n;
  int u,k,v,c;
  int mp[101][101],d[101];
  for(int i=0;i<=100;i++){
    d[i]=INF;
    for(int j=0;j<=100;j++)mp[i][j]=INF;
  }
    while(u!=n-1){
    cin>>u>>k;
    for(int i=0;i<k;i++){
      cin>>v>>c;
      if(mp[u][v]>c)mp[u][v]=c;
    }
  }
    d[0]=0;
    queue<int>p;
    p.push(0);
    int mn,s,cnt=n,t[101]={};
    t[0]=1;
    while(!p.empty()){
      s=p.back();
      mn=INF;
      for(int i=0;i<n;i++){
	if(t[i]==0){
	if(d[i]>d[s]+mp[s][i])d[i]=d[s]+mp[s][i];
	  if(mn>d[i])mn=d[i],k=i;
	}
      }
      if(mn!=INF)t[k]=1,p.push(k);
      else p.pop();
    }
    for(int i=0;i<n;i++)cout<<i<<" "<<d[i]<<endl;
    
  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define loop(i,a,b) for(i=a;i<b;i++)
#define rloop(i,a,b) for(i=a;i>=b;i--)
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
const int inf=1000000001;
const ll INF=1e16;
#define MOD 1000000007
#define mod 1000000009
#define pi 3.14159265358979323846
static const int WHITE=0;
static const int GRAY=1;
static const int BLACK=2;
static const int N=100;

int n;
vii m(N,vi(N));
vi d(N,inf);

void dijkstra();

int main(){
	int i,j;
	cin>>n;
	int u,k,v,c;
	loop(i,0,n){
		loop(j,0,n){
			m[i][j]=inf;
		}
	}
	loop(i,0,n){
		cin>>u>>k;
		loop(j,0,k){
			cin>>v>>c;
			m[u][v]=c;
		}
	}
	dijkstra();
	loop(i,0,n){
		cout<<i<<" "<<d[i]<<endl;
	}
}

void dijkstra(){
	int i;
	d[0]=0;
	vi color(n,WHITE);
	color[0]=BLACK;
	int u=0,v;
	while(1){
		int minv=inf;
		loop(i,0,n){
			if(color[i]!=BLACK){
				d[i]=min(d[i],d[u]+m[u][i]);
				if(minv>d[i]){
					minv=d[i];
					v=i;
				}
			}
		}
		if(minv==inf){
			break;
		}
		color[v]=BLACK;
		u=v;
	}
	
}

C++: #include <cstdio>
#include <vector>
#include <queue>
using namespace std;
const int MAX_V = 1e+4, INF = 1e+9;
struct edge {int to, cost;};
typedef pair<int, int> P; // 距離, 頂点
int n, d[MAX_V]; vector<edge> G[MAX_V];

void dijkstra(int s) {
  fill(d, d+n, INF); d[s] = 0;
  priority_queue<P, vector<P>, greater<P>> q;
  q.push(P(0, s));
  while(!q.empty()) {
    P p = q.top(); q.pop();
    int now = p.second;
    // 最短距離以外を無視
    if(d[now] < p.first) continue;
    for(int i = 0; i < G[now].size(); ++i) {
      edge e = G[now][i];
      if(d[e.to] > d[now] + e.cost) {
        d[e.to] = d[now] + e.cost;
        // とりあえず追加して、あとで最短距離以外を無視
        q.push(P(d[e.to], e.to));
      }
    }
  }
}
int main() {
  scanf("%d", &n);
  for(int i = 0, u, k; i < n; ++i) {
    scanf("%d %d", &u, &k);
    for(int j = 0, v, c; j < k; ++j) {
      scanf("%d %d", &v, &c);
      edge e = {v, c};
      G[u].push_back(e);
    }
  }
  dijkstra(0);
  for(int i = 0; i < n; ++i) {
    printf("%d %d\n", i, d[i]);
  }
}