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<vector>
#include<algorithm>
#include<utility>
#include<numeric>
#include<iostream>
#include<array>
#include<string>
#include<sstream>
#include<stack>
#include<queue>
#include<list>
#include<functional>
#define _USE_MATH_DEFINES

#include<math.h>
#include<map>

#define SENTINEL 1000000001

#define min(a,b) (a)>(b)?(b):(a)
#define max(a,b) (a)>(b)?(a):(b)

using namespace std;

/*struct OwnNode
{
	vector<int> to;
	vector<int> to_cost;

	int id;
	bool checked;
	int cost;

	OwnNode(int id):id(id),checked(false),cost(-1){}

	bool operator<(const OwnNode& node)const
	{
		return cost < node.cost;
	}

	bool operator>(const OwnNode& node)const
	{
		return cost > node.cost;
	}

	OwnNode operator-(const OwnNode& node)const
	{
		return cost - node.cost;
	}
};*/

int d[100][100];

int main()
{
	int n;
	cin >> n;

	for (int i = 0; i < n; i++)for (int j = 0; j < n; j++)
	{
		d[i][j] = 100000000;
	}

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

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

	for (int k = 0; k < n; k++)
	{
		for (int i = 0; i < n; i++)
		{
			for (int j = 0; j < n; j++)
			{
				d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
			}
		}
	}

	for (int i = 0; i < n; i++)
	{
		printf("%d %d\n", i, d[0][i]);
	}

	/*vector<OwnNode> nodes;

	for (int i = 0; i < n; i++)
	{
		int id, k;
		cin >> id >> k;

		nodes.push_back(OwnNode(id));

		for (int j = 0; j < k; j++)
		{
			int v, c;
			cin >> v >> c;
			nodes[i].to.push_back(v);
			nodes[i].to_cost.push_back(c);
		}
	}

	priority_queue<OwnNode, vector<OwnNode>, greater<OwnNode>> pq;

	nodes[0].cost = 0;
	pq.push(nodes[0]);

	while (pq.size() != 0)
	{
		OwnNode tn = pq.top();
		pq.pop();

		nodes[tn.id].checked = true;

		for (int i = 0; i != tn.to.size(); i++)
		{
			if (nodes[tn.to[i]].checked)continue;
			if (nodes[tn.to[i]].cost == -1)
			{
				nodes[tn.to[i]].cost = tn.to_cost[i];
			}
			else
			{
				nodes[tn.to[i]].cost = min(nodes[tn.to[i]].cost, tn.to_cost[i] + tn.cost);
			}
			pq.push(nodes[tn.to[i]]);
		}
	}

	for (auto& node : nodes)
	{
		
		printf("%d %d\n", node.id, node.cost);
	}*/

	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#define MAX 101
#define INF 1000001
using namespace std;

int n, isSelected[MAX], dist[MAX];
vector<pair<int, int>> ver[MAX];

void initDijkstra(void);
void dijkstra(void);
bool doesFinished(void);

int main() {
	int i, j, id, k, v, c;
	cin >> n;
	for (i = 0; i < n; i++) {
		cin >> id >> k;
		for (j = 0; j < k; j++) {
			cin >> v >> c;
			ver[id].push_back(make_pair(v, c));
		}
	}

	initDijkstra();

	while (!doesFinished())dijkstra();

	for (i = 0; i < n; i++) {
		cout << i << " " << dist[i] << endl;
	}

	return 0;
}

void initDijkstra(void) {

	dist[0] = 0;
	isSelected[0] = 1;
	for (int i = 1; i <= n; i++)dist[i] = INF;

	vector<pair<int, int>>::iterator itv;

	for (itv = ver[0].begin(); itv != ver[0].end(); itv++) {
		dist[itv->first] = itv->second;
	}

}

void dijkstra(void) {
	int i, minu, mindist = INF;
	vector<pair<int, int>>::iterator itv;

	for (i = 0; i < n; i++) {
		if (isSelected[i] == 0)continue;
		for (itv = ver[i].begin(); itv != ver[i].end(); itv++){
			if (isSelected[itv->first] == 1)continue;
			if (itv->second < mindist) {
				mindist = itv->second;
				minu = itv->first;
			}
		}
	}
	isSelected[minu] = 1;
	//dist[minu] = dist[minp] + mindist;
	for (itv = ver[minu].begin(); itv != ver[minu].end(); itv++) {
		if (isSelected[itv->first] == 1)continue;
		dist[itv->first] = min(dist[minu] + itv->second, dist[itv->first]);
	}
}

bool doesFinished(void) {
	for (int i = 0; i < n; i++) {
		if (isSelected[i] == 0)return false;
	}
	return true;
}

C++: #include <bits/stdc++.h>
using namespace std;

#define ll long long
#define vvi vector<vector<int>>
#define vec vector
#define pq priority_queue
#define all(v) (v).begin(), (v).end()
#define uniqueV(x) sort(x.begin(), x.end()); x.erase(unique(x.begin(), x.end()), x.end());
#define rep(i, n) for (int (i) = (0); (i) < (n); ++(i))
#define repp(i, m, n) for (int (i) = (m); (i) < (n); ++(i))
#define debug(x) cerr << #x << ": " << x << endl;
#define debug2(x, y) cerr<<"("<<#x<<", "<<#y<<") = "<<"("<<x<<", "<<y<<")"<<endl;
#define debug3(x, y, z) cerr<<"("<<#x<<", "<<#y<<", "<<#z<<") = "<<"("<<x<<", "<<y<<", "<<z<<")"<<endl;
#define debugB(x, y) cerr<<#x<<": "<<bitset<y>(x) << endl;
#define line() cerr << "---------------" << endl;

const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, -1, 1};
const double PI = 3.14159265358979323846;

template<typename T>
void printA(vector<T> &printArray, char between = ' ') {
   int paSize = printArray.size();
   for (int i = 0; i < paSize; i++) { cerr << printArray[i] << between;}
   if (between != '\n') {cerr << endl;}
}

// ------------------------------------------------------------------------------------------

struct edge { int to, cost; };
using P = pair<int, int>;

const int INF = 1e8;
int n;
vec<vec<edge>> G;
int d[111];

void dijkstra(int s) {
   priority_queue<P, vec<P>, greater<P>> Q;
   fill(d, d + n, INF);
   d[s] = 0;
   Q.push({0, s});

   while (Q.size()) {
      P p = Q.top(); Q.pop();
      int v = p.second;
      if (d[v] < p.first) continue;
      for (int i = 0; i < G[v].size(); i++) {
         edge e = G[v][i];
         if (d[e.to] > d[v] + e.cost) {
            d[e.to] = d[v] + e.cost;
            Q.push({d[e.to], e.to});
         }
      }
   }
}

int main() {
   cin >> n;
   G = vec<vec<edge>>(n);
   rep (i, n) {
      int u, k;
      cin >> u >> k;
      rep (j, k) {
         int v, c;
         cin >> v >> c;
         G[u].push_back({v, c});
      }
   }

   dijkstra(0);

   rep (i, n) {
      printf("%d %d\n", i, d[i]);
   }

   return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;

const int inf = 1<<29;
int n;
vector<pair<int, int>> G[110];
vector<int> d(110, inf);

void dijkstra(int s){
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> qu;
    d[s] = 0;
    qu.push(make_pair(0, s));

    while(!qu.empty()){
        pair<int, int> p = qu.top(); qu.pop();
        if(d[p.second] < p.first) continue;
        for(auto e:G[p.second]){
            if(d[e.second] > p.first+e.first){
                d[e.second] = p.first+e.first;
                qu.push(make_pair(d[e.second], e.second));
            }
        }
    }
}

int main(){
    cin >> n;
    for(int i=0; i<n; ++i){
        int u, k; cin >> u >> k;
        for(int j=0; j<k; ++j){
            int v, w; cin >> v >> w;
            G[u].push_back(make_pair(w, v));
        }
    }

    dijkstra(0);
    for(int i=0; i<n; ++i){
        cout << i << ' ' << d[i] << '\n';
    }

    return 0;

}