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 <cstdio>
#include <vector>
#include <climits>

class Graph{
public:
	std::vector< std::vector<int> > A;
	int n;

	Graph(int n);

	void SetEdge(int a, int b, int weight);
	void SortEdge();
	void SortEdge_Rec1(int left, int right);
	void SortEdge_Rec2(int left, int mid, int right);

	std::vector<int> Dijkstra();

};

Graph::Graph(int n){
	A.resize(n);
	for (int i = 0; i < n; i++) A[i].resize(n, -1);
	this->n = n;
}

void Graph::SetEdge(int a, int b, int weight){
	A[a][b] = weight;
	return;
}
/*
void Graph::SortEdge(){
	SortEdge_Rec1(0, A.size());
}

void Graph::SortEdge_Rec1(int left, int right){
	if (left + 1 < right){
		int mid = (left + right) / 2;
		SortEdge_Rec1(left, mid);
		SortEdge_Rec1(mid, right);
		SortEdge_Rec2(left, mid, right);
	}
}

void Graph::SortEdge_Rec2(int left, int mid, int right){
	int n1 = mid - left;
	int n2 = right - mid;
	std::vector< std::vector<int> > L(n1 + 1);
	for (int i = 0; i < n1; i++) L[i] = A[left + i];
	std::vector< std::vector<int> > R(n2 + 1);
	for (int i = 0; i < n2; i++) R[i] = A[mid + i];
	std::vector<int> x;
	x.push_back(0); x.push_back(0); x.push_back(INFTY);
	L[n1] = x;
	R[n2] = x;
	int i = 0;
	int j = 0;
	for (int k = left; k < right; k++){
		if (L[i][2] <= R[j][2]){
			A[k] = L[i];
			i = i + 1;
		}
		else{
			A[k] = R[j];
			j = j + 1;
		}
	}
}
*/
std::vector<int> Graph::Dijkstra(){
	std::vector<int> d(n, INT_MAX), prev(n, -1), Q(n, 0);
	d[0] = 0;
	for (int i = 0; i < n; i++) Q[i] = i;

	while (!Q.empty()){
		int mini, minu;
		for (int i = 0; i < Q.size(); i++){
			if (i == 0 || d[Q[i]] < d[minu]){
				minu = Q[i];
				mini = i;
			}
		}
		Q.erase(Q.begin() + mini);
		for (int i = 0; i < n; i++){
			if (A[minu][i] != -1){
				if (d[i] > d[minu] + A[minu][i]){
					d[i] = d[minu] + A[minu][i];
					prev[i] = minu;
				}
			}
		}
	}
	return d;
}

int main(){
	int n, u, k, v, c;
	scanf("%d", &n);
	Graph G(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);
			G.SetEdge(u, v, c);
		}
	}
	std::vector<int> result = G.Dijkstra();
	for (int i = 0; i < n; i++) printf("%d %d\n", i, result[i]);

	return 0;
}

C++: #include<bits/stdc++.h>
#define rep(i,n) for(int i=0;i< (n);i++)
using namespace std;
typedef long long ll;
const int INF = 1e+7;
typedef pair<int,int> P;

struct dijkstra{
    vector<int> color;
    vector<vector<P>> adj;
    vector<int> d;
    vector<int> p;
    int n_;
    dijkstra(int n):color(n,0),adj(n),d(n,INF),p(n,-1){
        n_ = n;
    }
    void init(){
        rep(i,n_){
            int u,k;cin>>u>>k;
            rep(j,k){
                int v,c;cin>>v>>c;
                P tmp = make_pair(v,c);
                adj[i].push_back(tmp);
            }
        }
    }
    void solve(){
        init();
        d[0] = 0;
        p[0] = -1;
        while(true){
            int mincost = INF;
            int u;
            rep(i,n_){
                if(color[i]!=2 && d[i]<mincost){
                    mincost = d[i];
                    u = i;
                }
            }
            if(mincost == INF)break;
            color[u] = 2;
            for(P v:adj[u]){    
                if(color[v.first]!=2 && d[u]+v.second < d[v.first]){
                    d[v.first] = d[u] + v.second;
                    p[v.first] = u;
                    color[v.first] = 1;
                }
            }
        }
        rep(i,n_){
            cout<<i<<" "<<d[i]<<endl;
        }
    }
};


int main(){
    int n;cin>>n;
    dijkstra dj(n);
    dj.solve();
    return 0;
}

C++: #include <iostream>
#include <fstream>
#include <stdio.h>
#include <algorithm>

using namespace std;

static const int MAX = 100;
static const int INFTY = (1 << 21);
static const int WHITE = 0;
static const int BLACK = 1;

int n;
int M[MAX][MAX];

void prim(){
    int minv;
    int d[MAX], color[MAX];
    
    for(int i=0; i<n; i++){
        d[i] = INFTY;
        color[i] = WHITE;
    }
    
    d[0] = 0;
    
    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 i=0; i<n; i++){
            if(M[u][i] != INFTY && color[i] != BLACK){
                if(d[i] > d[u]+M[u][i]){
                    d[i] = d[u]+M[u][i];
                }
            }
        }
    }
    
    for(int i=0; i<n; i++){
        cout << i << " " << (d[i] == INFTY ? -1 : d[i]) << endl;
    }
}

int main(int argc, const char * argv[]) {
    // input from txt
    
    /////////
    //write//
    /////////
    
    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;
        }
    }
    
    prim();
    
    return 0;
}

C++: #include <stdio.h>
#include <iostream>
using namespace std;

#define NIL -1
#define INF 100000000
#define WHITE 1
#define GREY 2
#define BLACK 3
#define N_MAX 100

int G[N_MAX][N_MAX];
int V[N_MAX];
int V_value[N_MAX];

void init(){
    for(int i = 0; i < N_MAX; i++){
        V[i] = WHITE;
        V_value[i] = INF;
    }

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

int main(void){
    init();
    int n;
    scanf("%d\n", &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);
            G[u][v] = c;
        }
    }

    V[0] = BLACK;
    V_value[0] = 0;
    int new_node = 0;
    
    while(1){
        for(int i = 0; i < n; i++){
            if(G[new_node][i] != NIL && V[i] == WHITE){
                V_value[i] = min(V_value[i], V_value[new_node] + G[new_node][i]);
            }
        }

        int min_index = NIL;
        int min_value = INF;
        for(int i = 0; i < n; i++){
            if(V[i] == WHITE && V_value[i] < min_value){
                min_value = V_value[i];
                min_index = i;
            }
        }
        if(min_index == NIL){
            break;
        }else{
            new_node = min_index;
            V[new_node] = BLACK;
            V_value[new_node] = min_value;
        }
    }
    
    for(int i = 0; i < n; i++){
        printf("%d %d\n", i, V_value[i]);
    }

    return 0;
}