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 <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <cctype>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#include <functional>

using namespace std;
using ll = long long int;
#define rep(i,n) for(int i = 0; i < n; i++)
#define FOR(i, a, b)  for(int i = (a); i < (b) ; i++)

#define pb push_back
#define SORT(v,n) sort(v, v+n)
#define ALL(x) (x).begin(),(x).end()
#define debug(x) cerr << #x << ": " << x << '\n'
#define elif else if
#define itn ll
#define int ll
const int INF = 100100100;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;
///                →,↑,←,↓,↗,↖,↙,↘
int dx[8] = { 1, 0, -1, 0, 1, -1, -1, 1 };
int dy[8] = { 0, 1, 0, -1, 1, 1, -1, -1 };

typedef vector<vector<int>> vvi;
typedef vector<vector<vector<int>>> vvvi;

static const int MAX = 100;
static const int White = 0;
static const int Gray = 1;
static const int Black = 2;


int n, M[MAX][MAX];
int d[MAX], p[MAX],color[MAX];

void dijkstra() {
	rep(i, n) {
		color[i] = White;
		d[i] = INF;
		p[i] = -1;
	}
	d[0] = 0;
	while (true) {
		int u, mincost = INF;
		rep(i, n) {
			if (color[i] != Black and d[i] < mincost) {
				u = i;
				mincost = d[i];
			}
		}
		if (mincost == INF) break;
		color[u]  = Black;
		int v;
		rep(v, n) {
			if (color[v] != Black and M[u][v] != INF) {
				if (d[u] + M[u][v] < d[v]) {
					d[v] = d[u] + M[u][v];
					p[v] = u;
					color[v] = Gray;
				}
			}
		}
	}
	rep(i, n) {
		cout << i << ' ' << d[i] << '\n';
	}
}

signed main() {
	ios::sync_with_stdio(false);
	int i, j, k;
	cin >> n;
	rep(i, n) {
		rep(j, n) {
			M[i][j] = INF;
		}
	}
	rep(i, n) {
		int u, k;
		cin >> u >> k;
		rep(j, k) {
			int c,v;
			cin >> v >> c;
			M[u][v] = c;
		}
	}
	dijkstra();
	return 0;
}

C++: #include<stdio.h>

#define N 103
#define INF 10000000
#define NIL -1
#define BLACK 1

int G[N][N];

int d[N],pi[N],color[N];
int ci[N];
int v[N];

int num;

void initialize(int);
void dij(int);

int main(){
  int i,j;
  int k,u;
  int start=0;

  scanf("%d",&num);

  for(i=0;i<num;i++){
    for(j=0;j<num;j++){
      G[i][j] = NIL;
    }
  }
  

  for(i=0;i<num;i++){
    scanf("%d%d",&u,&k);
      for(j=0;j<k;j++){
	scanf("%d%d",&v[j],&ci[j]);
	G[u][v[j]] = ci[j]; 
      }
  }

  dij(start);

  /*for(i=0;i<num;i++){
    for(j=0;j<num;j++){
      printf("%d ",G[i][j]);
    }
    printf("\n");
  }
  */

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

}

void initialize(int s){
  int v;
  for(v=0;v<num;v++){
    d[v] = INF;
    pi[v] = NIL;
  }

  d[s] = 0;
}

void dij(int s){
  int mincost;
  int i,v,u;
  
  initialize(s);

  while(1){
    
    mincost = INF;

    for(i=0;i<num;i++){
      
      if(color[i] != BLACK && d[i] < mincost){
	mincost = d[i];
	u = i;

      }
    }

    //printf("u=%d\n", u);
    if(mincost == INF) break;

    color[u] = BLACK;
    
    for(v=0;v<num;v++){
      
      if(G[u][v] == -1) continue;
      if(color[v] != BLACK && d[u] + G[u][v] < d[v]){
	pi[v]= u;
	d[v] = d[u] + G[u][v];
      }
    }
  }
}

C++: #include <iostream>
#include <vector>
#include <utility>
#include <queue>
// #include <string>
using namespace std;

vector<string> split(string s, string delimiter)
{
    int pos_start = 0, pos_end, delim_len = delimiter.length();
    string token;
    vector<string> res;

    while ((pos_end = s.find(delimiter, pos_start)) != string::npos)
    {
        token = s.substr(pos_start, pos_end - pos_start);
        pos_start = pos_end + delim_len;
        res.push_back(token);
    }

    res.push_back(s.substr(pos_start));
    return res;
}

vector<int> dijkstra(int n, vector<vector<int>> adj_matrix)
{
    vector<int> d(n, 1e9);
    vector<int> prev(n);
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> Q;

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

    while (!Q.empty())
    {
        int u = Q.top().second;
        // int c = Q.top().first;
        Q.pop();

        for (int i = 0; i < n; i++)
        {
            if (adj_matrix[u][i] > 0)
            {
                int tmp = d[u] + adj_matrix[u][i];
                if (tmp < d[i])
                {
                    d[i] = tmp;
                    prev[i] = u;
                    Q.push(make_pair(d[i], i));
                }
            }
        }
    }

    return d;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;
    cin.ignore();
    vector<vector<int>> adj_matrix;
    adj_matrix.resize(n);
    for (int i = 0; i < adj_matrix.size(); i++)
    {
        adj_matrix[i].resize(n);
    }

    for (int i = 0; i < n; i++)
    {
        string s;
        getline(cin, s);
        vector<string> tmp = split(s, " ");
        int u = stoi(tmp[0]);
        int k = stoi(tmp[1]);

        for (int j = 2; j < tmp.size(); j += 2)
        {
            int v = stoi(tmp[j]);
            adj_matrix[u][v] = stoi(tmp[j + 1]);
        }
    }

    vector<int> ans = dijkstra(n, adj_matrix);
    for (int i = 0; i < n; i++)
    {
        cout << i << " " << ans[i] << endl;
    }

    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;
}