Go: package main

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

const BIG_COST = 200000

const (
	ST_NOT_YET = iota
	ST_JOINED
)

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	nNodes := scanInt(sc)

	costs := make([][]int, nNodes)
	graph := make([][]int, nNodes)

	states := make([]int, nNodes)
	costSums := make([]int, nNodes)

	for i := 0; i < nNodes; i++ {
		costs[i] = make([]int, nNodes)
		costSums[i] = BIG_COST
	}

	for i := 0; i < nNodes; i++ {
		u := scanInt(sc)
		k := scanInt(sc)
		graph[u] = make([]int, k)
		for d := 0; d < k; d++ {
			v := scanInt(sc)
			graph[u][d] = v
			costs[u][v] = scanInt(sc)
		}
	}

	costSums[0] = 0
	for {
		minCost := BIG_COST
		var u int

		for i, cost := range costSums {
			if states[i] != ST_JOINED && cost < minCost {
				minCost = cost
				u = i
			}
		}

		if minCost == BIG_COST {
			break
		}

		states[u] = ST_JOINED

		for _, v := range graph[u] {
			cost := minCost + costs[u][v]
			if cost < costSums[v] {
				costSums[v] = cost
			}
		}
	}

	w := bufio.NewWriter(os.Stdout)
	for i, cost := range costSums {
		fmt.Fprintf(w, "%d %d\n", i, cost)
	}
	w.Flush()
}

func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

C++: #include <bits/stdc++.h>
#include <string.h>
#include <cmath>
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define max3(A,B,C) max((A),max((B),(C)))
#define popcount(X) __builtin_popcount(X)
#define popcountl(X) __builtin_popcountl(X)
#define getbit(x,i) (1&((x)>>(i)))
#define setbit(x,i,bit) ((x)|=((bit)<<(i)))
#define getbitl(x,i) (1&((x)>>((ll)i)))
#define setbitl(x,i,bit) ((x)|=((bit)<<((ll)i)))
#define log2(x) (32 - __builtin_clz(x))
#define log2l(x) (32 - __builtin_clzl(x))

using namespace std;

typedef long long int ll;
typedef unsigned long long int ull;
typedef pair<ll,ll> ii;
typedef vector<ll> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef vector<vii> vvii;

const int INF = 0x3f3f3f3f;
const long long int INFL = 0x3f3f3f3f3f3f3f3f;
const double pi = atan(1.0)*4.0;
const int N = 3e5 + 500;

int dist[N], mrc[N];
vii v[N];
set<ii> st;

void Dijkstra(int o, int n) {
	memset(dist,INF,sizeof(dist));
	st.clear();
	st.insert(mp(0,o));
	dist[o] = 0;
	for(int i = 0; i < n; i++) if(i != o) st.insert(mp(INF,i));
	memset(mrc,0,sizeof(mrc));
	while(!st.empty()) {
		set<ii>::iterator it = st.begin();
		if(mrc[it->s] == 0) {
			mrc[it->s] = 1;
			for(int i = 0; i < v[it->s].size(); i++) {
				if(dist[it->s] + v[it->s][i].s < dist[v[it->s][i].f]) {
					st.erase(mp(dist[v[it->s][i].f], v[it->s][i].f));
					dist[v[it->s][i].f] = dist[it->s] + v[it->s][i].s;
					st.insert(mp(dist[v[it->s][i].f], v[it->s][i].f));
				}
			}
		}
		st.erase(it);
	}
}


int main(void) {
	int n;
	
	scanf("%d", &n);
	
	for(int i = 0; i < n; i++) {
		int u, k;
		scanf("%d %d", &u, &k);
		for(int j = 0; j < k; j++) {
			int vt, c;
			scanf("%d %d", &vt, &c);
			v[u].pb(mp(vt,c));
		}
	}
	Dijkstra(0,n);
	for(int i = 0; i < n; i++) {
		printf("%d %d\n", i, dist[i]);
	}
	
	return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<cstring>
#define INF 2100
using namespace std;
int n;
int A[1000][1000];
int d[1000];
bool used[1000];
int D[1000][1000];
 
void Init(int f){
  for(int i=0;i<f;i++){
    for(int j=0;j<f;j++)D[i][j] = INF;
  }
 
}
 
int main(){
  scanf("%d",&n);
  int u,k,C,V;
  Init(n);
  
  for(int i=0;i<n;i++){
      scanf("%d %d",&u,&k);     
      for(int j=0;j<k;j++){
    scanf("%d %d",&V,&C);
    D[u][V] = C;
    D[V][u] = C;
      }     
  }
   
  for(int i=0;i<n;i++)D[i][i] = 0;
  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]);
  }
 
  return 0;
}

C++: #include <climits>
#include <iostream>
#include <utility>
#include <vector>

using namespace std;

void dijkstra(vector<vector<pair<int, int>>>& g, vector<int>& weights) {
    int n_vertex = weights.size();
    vector<bool> visited(n_vertex, false);
    weights[0] = 0;
    while (true) {
        int min_idx;
        int min_weight = INT_MAX;
        for (int i = 0; i < n_vertex; ++i) {
            if (!visited[i] && weights[i] < min_weight) {
                min_idx = i;
                min_weight = weights[i];
            }
        }

        if (min_weight == INT_MAX)
            break;

        visited[min_idx] = true;

        for (int i = 0; i < g[min_idx].size(); ++i) {
            int adj = g[min_idx][i].first;
            int weight_via_idx = weights[min_idx] + g[min_idx][i].second;
            if (!visited[adj] && weight_via_idx < weights[adj]) {
                weights[adj] = weight_via_idx;
            }
        }
    }
}

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

    vector<vector<pair<int, int>>> g(n);
    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;
            g[i].push_back(make_pair(v, c));
        }
    }

    vector<int> weights(n, INT_MAX);
    dijkstra(g, weights);
    for (int i = 0; i < n; ++i)
        cout << i << ' ' << weights[i] << '\n';
}

C++: #include <bits/stdc++.h>
using namespace std;
#define MAX 100
#define INFTY (1<<21)
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n, M[MAX][MAX];

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

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

  d[0] = 0;
  color[0] = GRAY;
  while ( 1 ) {
    minv = INFTY;
    int u = -1;
    for ( int 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 (int v = 0; v < n; v++) {
      if (color[v] != BLACK && M[u][v] != INFTY) {
        if (d[v]> d[u] + M[u][v]) {
          d[v] = d[u] + M[u][v];
          color[v] = 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 j = 0; j < n; j++) {
      M[i][j] = INFTY;
    }
  }
  int k, c, u, v;
  for (int i = 0; i < n; i++) {
    cin >> u >> k;
    for (int j = 0; j<k;j++) {
      cin >> v >> c;
      M[u][v] = c;
    }
  }
  dijkstra();

  return 0;
}

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

using ll = long long int;
using P = pair<int,int>;
constexpr int INF = 1<<30;

int n;
vector<vector<P> > g;
vector<int> d;

void dijkstra(int s){
    fill(d.begin(), d.end(), INF);
    d[s] = 0;
    priority_queue<P, vector<P>, greater<P> > que;
    que.push(make_pair(d[s],s));

    while(!que.empty()){
        P p = que.top();
        que.pop();
        int v = p.second;
        if(d[v] < p.first) continue;
        int k = int(g[v].size());
        for(int i=0;i<k;i++){
            int u = g[v][i].first, c = g[v][i].second;
            if(d[u] > d[v] + c){
                d[u] = d[v] + c;
                que.push(make_pair(d[u], u));
            }
        }
    }
}

int main(){
    cin >> n;
    g.resize(n);
    d.resize(n);
    for(int i=0;i<n;i++){
        int v, k;
        cin >> v >> k;
        for(int j=0;j<k;j++){
            int u, c;
            cin >> u >> c;
            g[v].push_back(make_pair(u,c));
        }
    }
    dijkstra(0);
    for(int i=0;i<n;i++){
        cout << i << " " << d[i] << endl;
    }
    return 0;
}