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 <cstdio>
#include <vector>
#include <queue>
using namespace std;
const int MAX_V = 1e+4, INF = 1e+9;
struct edge {int to, cost;};
typedef pair<int, int> P; // 距離, 頂点
int n, d[MAX_V]; vector<edge> G[MAX_V];

void dijkstra(int s) {
  fill(d, d+n, INF); d[s] = 0;
  priority_queue<P, vector<P>, greater<P>> q;
  q.push(P(0, s));
  while(!q.empty()) {
    P p = q.top(); q.pop();
    int now = p.second;
    // 最短距離以外を無視
    if(d[now] < p.first) continue;
    for(int i = 0; i < G[now].size(); ++i) {
      edge e = G[now][i];
      if(d[e.to] > d[now] + e.cost) {
        d[e.to] = d[now] + e.cost;
        // とりあえず追加して、あとで最短距離以外を無視
        q.push(P(d[e.to], e.to));
      }
    }
  }
}
int main() {
  scanf("%d", &n);
  for(int i = 0, u, k; i < n; ++i) {
    scanf("%d %d", &u, &k);
    for(int j = 0, v, c; j < k; ++j) {
      scanf("%d %d", &v, &c);
      edge e = {v, c};
      G[u].push_back(e);
    }
  }
  dijkstra(0);
  for(int i = 0; i < n; ++i) {
    printf("%d %d\n", i, d[i]);
  }
}

C++: #include <iostream>
#include <vector>
#define INFTY 10000000
using namespace std;
int n,G[100][100];
int d[100],flag[100];
vector<int>path;
void dijkstra(){
    path.push_back(0);
    //int distance=0;
    int mini,min;
    while(path.size()<n){
        min=INFTY;
        int index=path.size()-1;
        //distance+=path[path.size()-1];
        for(int i=1;i<n;i++)
        {
            int temp=d[path[index]]+G[path[index]][i];
            if(d[i]>temp)
                d[i]=temp;
        }
        for(int i=1;i<n;i++)
        {
            if(flag[i])continue;
            if(d[i]<min)
            {
                min=d[i];
                mini=i;
            }
        }
        path.push_back(mini);
        flag[mini]=1;
        //distance+=path[path.size()-1];
    }
}
int main()
{
    int u,k,v,c;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        d[i]=INFTY;
        flag[i]=0;
        for(int j=0;j<n;j++)
            G[i][j]=INFTY;
    }
    for(int i=0;i<n;i++)
    {
        cin>>u>>k;
        for(int j=0;j<k;j++)
        {
            cin>>v>>c;
            G[u][v]=c;
        }
    }
    d[0]=0;
    dijkstra();
    for(int i=0;i<n;i++)
        cout<<i<<' '<<d[i]<<endl;
    return 0; 
}

C++: #include <iostream>

using namespace std;

static const int MAX = 100;
static const int INFTY = (1<<21);
static const int WHITE = 0;
static const int GRAY = 1;
static const int 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 << " ";
		if(d[i] == INFTY) cout << -1 << endl;
		else cout << 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<iostream>
#include<cstdio>
#define W 0
#define G 1
#define B 2
#define inf 1000000
#define MAX 100
#define NIL -1
using namespace std;

int n;
int A[MAX][MAX];

void Prim(){
    int color[MAX],d[MAX],p[MAX];
    int min,u;
    for(int i = 0; i < n; i++){
        color[i] = W;
        d[i] = inf;
        p[i] = NIL;
    }
    
    d[0] = 0;
    
    while(1){
        u = -1;
        min = inf;
        for(int i = 0; i < n; i++){
            if(d[i] < min && color[i] != B){
                u = i;
                min = d[i];
            }
        }
        
        if(u == -1) break;
            
        color[u] = B;
            
        for(int i = 0; i < n; i++){
            if(color[i] != B && A[u][i] != NIL){
                if(A[u][i] + d[u] < d[i]){
                    d[i] = A[u][i] + d[u];
                    color[i] = G;
                    p[i] = u;
                }
            }
        }
    }
    
    for (int i = 0; i < n; i++){
        printf("%d %d\n",i,d[i]);
    }
}

int main(){
    int u,k,c,v;
    scanf("%d",&n);
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n; j++){
            A[i][j] = inf;
        }
    }
    for(int i = 0; i < n; i++){
        scanf("%d %d", &u, &k);
        for(int j =0; j < k; j++){
            scanf("%d %d",&v,&c);
            A[i][v] = c;
        }
    }
    
    
    Prim();
    return 0;
}

C++: // -*- mode:c++; coding:utf-8; c-basic-offset:2; -*-
// ALDS1_12_B: Single Source Shortest Path I

#include <algorithm>
#include <cstdio>

using uint = unsigned int;

class Graph {
  const uint n_;
  uint* const g_;
  const uint INFINIT;
  
public:

  Graph(uint n) : n_(n), g_(new uint[(n_*n_)]), INFINIT(100000*n_) {
    std::fill_n(g_, (n_*n_), INFINIT);
  }

  ~Graph() { delete[] g_; }
  
  uint* operator [](uint i) const { return g_+(n_*i); }

  void dijkstra(uint* dist)
  {
    std::fill_n(dist, n_, INFINIT);
    bool visited[n_];
    std::fill_n(visited, n_, false);
    auto i = 0u; // 0-start
    visited[i] = true;
    dist[i] = 0u;
    for (auto n = 0u; n < n_-1; ++n) {
      auto cur_min = INFINIT;
      auto es = (*this)[i];
      auto base_dist = dist[i];
      for (auto j = 0u; j < n_; ++j) {
        if (visited[j]) continue;
        dist[j] = std::min(dist[j], base_dist+es[j]);
        if (cur_min > dist[j]) {
          cur_min = dist[j];
          i = j;
        }
      }
      visited[i] = true;
      dist[i] = cur_min;
    }
  }
};

int main()
{
  uint n;
  std::scanf("%u", &n);

  Graph g(n);

  uint u, k, c, v;
  for (auto i = 0u; i < n; ++i) {
    std::scanf("%u %u", &u, &k);
    for (auto j = 0u; j < k; ++j) {
      std::scanf("%u %u", &c, &v);
      g[u][c] = v;
    }
  }

  uint dist[n];
  g.dijkstra(dist);
  for (auto i = 0u; i < n; ++i) {
    std::printf("%u %u\n", i, dist[i]);
  }
}

// eof