Go: package main

import (
	"strconv"
	"fmt"
	"bufio"
	"os"
)
const INF = 1 << 21
var scanner = bufio.NewScanner(os.Stdin)

func nextInt() int {
	scanner.Scan()
	i, e := strconv.Atoi(scanner.Text())
	if e != nil {
		panic(e)
	}
	return i
}


func main() {
	scanner.Split(bufio.ScanWords)
	n := nextInt()
	adj := make([][]int, n)
	for i := range adj {
		adj[i] = make([]int, n)
	}

	for i := 0;i < n; i++ {
		u := nextInt()
		k := nextInt()
		for j := 0; j < k; j++ {
			v := nextInt()
			c := nextInt()
			adj[u][v] = c
		}
	}

	// for i := range adj {
	// 	fmt.Println(adj[i])
	// }

	dist := make([]int, n)
	prev := make([]int, n)
	visited := make([]bool, n)
	dijkstra := func(start int, size int) {
		for i := 0; i < size; i++ {
			dist[i] = INF
			prev[i] = -1
			visited[i] = false
		}
		dist[start] = 0
		for {
			u := -1
			tmp_min := INF
			for i := 0; i < size; i++ {
				if visited[i] == false && dist[i] < tmp_min {
					tmp_min = dist[i]
					u = i
				}
			}
			if u == -1 {
				break
			}
			visited[u] = true
			for i := 0; i < size; i++ {
				if adj[u][i] > 0 {
					w := adj[u][i]
					newlen := dist[u] + w
					if newlen < dist[i] {
						dist[i] = newlen
						prev[i] = u
					}
				}
			}
		}
	}
	dijkstra(0, n)
	for i, cost := range dist {
		fmt.Printf("%d %d\n", i, cost)
	}
}

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; };
struct P { 
   int dist, number; 
   bool operator<(const P &p) const {
      return dist < p.dist;
   }
   bool operator>(const P &p) const {
      return dist > p.dist;
   }
};
 
const int INF = 1e8;
int n;
vec<vec<edge>> G;
int d[111];

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

   while (Q.size()) {
      P p = Q.top(); Q.pop();
      int v = p.number;
      if (d[v] < p.dist) 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() {
   // 入力
   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});
      }
   }
 
   // ダイクストラ法
   dijkstra(0);
 
   // 出力
   printDist();
 
   return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<(b);++i)
#define erep(i,a,b) for(int i=a;i<=(int)(b);++i)
#define per(i,a,b) for(int i=(b);i>(a);--i)
#define eper(i,a,b) for(int i=((int)(a));i>=b;--i)
#define pb push_back
#define mp make_pair
#define INF 2000000000
#define MOD 1000000007
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
int dy[]={0, 0, 1, -1};
int dx[]={1, -1, 0, 0};
int gcd(int a,int b){return b?gcd(b,a%b):a;}
int lcm(int a,int b){return a/gcd(a, b)*b;}

int n, d[100005];
struct edge{int to, cost;};
vector<edge> g[100005];
int main() {
 ios::sync_with_stdio ( false );
 cin.tie ( 0 );
    cin >> n;
    rep(i, 0, n) {
        int u, k;
        cin >> u >> k;
        rep(j, 0, k) {
            int v, c;
            cin >> v >> c;
            edge e;
            e.to = v, e.cost = c;
            g[u].pb(e);
        }
    }

    priority_queue<P, vector<P>, greater<P> > que;
    fill(d, d+n, INF);
    d[0] = 0;
    que.push({d[0], 0});
    while (!que.empty()) {
        P p = que.top(); que.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;
                que.push(P(d[e.to], e.to));
            }
        }
    }
    rep(i, 0, n) {
        cout << i << " " << d[i] << endl;
    }
    return 0;
}

C++: //ALDS1_12B
#include <iostream>
using namespace std;

static const int MAX=100;
static const int INF=(1<<21);
static const int WHITE=0;
static const int GRAY=1;
static const int BLACK=2;

int n,M[MAX][MAX];

int dijkstra(){
 int minv;
 int d[MAX],color[MAX];
 for(int i=0;i<n;i++){
  d[i]=INF;
  color[i]=WHITE;
 }
 d[0]=0;
 color[0]=GRAY;
 while(true){
  minv=INF;
  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]!=INF){
    if(d[v]>M[u][v]){
     d[v]=d[u]+M[u][v];
     color[v]=GRAY;
    }
   }
  }
 }
 for(int i=0;i<n;i++){
  cout<<i<<" "<<(d[i]==INF ? -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]=INF;
  }
 }
 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;
}