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 <vector>
using namespace std;

const int MAX = 100;
const int INFTY = (1 << 21);
int n;
int M[MAX][MAX];

void dijkstra(int s){
  int color[MAX], d[MAX], p[MAX];
  // vector<int> S;
  for(int i=0;i<n;i++){
    color[i] = 0;
    d[i] = INFTY;
    p[i] = -1;
  }
  d[s] = 0;
  p[s] = -1;
  color[0] = 1;

  while(true){
    int mincost = INFTY;
    int u = -1;
    for(int i=0;i<n;i++){
      if(color[i] != 2 && d[i] < mincost){
        mincost = d[i];
        u = i;
      }
    }

    // if(mincost == INFTY) break;
    if(u == -1) break;
    color[u] = 2;

    // S.push_back(u);
    for(int i=0;i<n;i++){
      if(M[u][i] != -1 && (d[i] > M[u][i] + d[u])){
        d[i] = M[u][i] + d[u];
        color[i] = 1;
        p[i] = u;
      }
    }
  }

  for(int i=0;i<n;i++){
    cout << i << " " << 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;

  for(int i=0;i<n;i++){
    int id, k, v, c;
    cin >> id >> k;
    for(int j=0;j<k;j++){
      cin >> v >> c;
      M[id][v] = c;
    }
  }

  dijkstra(0);
  return 0;
}

C++: #include <cstdio>
#include <queue>
#include <utility>
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;
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[i] = 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;
                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;
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
#define INF 9999999
using namespace std;

const int maxn = 10000 + 5;
const int maxm = 500000 + 5;

struct Edge{
	int next;
	int to;
	int value;
	Edge():next(0),to(0),value(INF){}
}G[maxm];

struct Node{
	int to;
	int dist;
	bool operator < (const Node& rhs) const{
		return dist > rhs.dist;
	}
};

int head[maxn],cnt;
int dis[maxn];
bool vis[maxn];

int n;

void Insert(int u,int v,int c){
	G[++cnt].next = head[u];
	G[cnt].to = v;
	G[cnt].value = c;
	head[u] = cnt;
}

void init(){
	memset(dis,INF,sizeof(dis));
	memset(vis,false,sizeof(vis));
}

priority_queue<Node >Q;

void Dijkstar(int s){
	dis[s] = 0;
	Q.push((Node){s,0});
	while(!Q.empty()){
		int u = Q.top().to;Q.pop();
		if(vis[u])continue;
		vis[u] = true;
		for(int e = head[u];e; e = G[e].next){
			int v = G[e].to;
			if(dis[u] + G[e].value < dis[v] && !vis[v]){
				dis[v] = dis[u] + G[e].value;
				Q.push((Node){v,dis[v]});
			}
		}
	}
}

int main(){
	init();
	scanf("%d",&n);
	for(int i = 0;i < n; i++){
		int u,m;
		scanf("%d%d",&u,&m);
		for(int j = 0;j < m; j++){
			int v,c;
			scanf("%d%d",&v,&c);
			Insert(u,v,c);
		}
	}
	Dijkstar(0);
	for(int i = 0;i < n; i++){
		printf("%d %d\n",i,dis[i]);
	}
}

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_-1)+1) {
    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);
    auto i = 0u; // 0-start
    dist[i] = 0u;
    for (auto n = 0u; n < n_-1; ++n) {
      auto cur_min = INFINIT;
      auto cs = (*this)[i];
      auto c = dist[i];
      for (auto j = 0u; j < n_; ++j) {
        auto nc = c+cs[j];
        if (dist[j] < nc) continue;
        dist[j] = nc;
        if (cur_min > nc) {
          i = j;
          cur_min = nc;
        }
      }
    }
  }
};

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

  Graph g(n);

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

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

// eof

C++: #include <iostream>
using namespace std;
const int MAXn = 100;
const int INFTY = 1 << 21;

int n, M[MAXn][MAXn], col[MAXn], d[MAXn], p[MAXn];

void dijkstra(int s) {
    for(int i = 0; i < n; i++) {
        col[i] = 0;
        d[i] = INFTY;
    }
    d[s] = 0;
    p[s] = -1;

    while(1) {
        int mincost = INFTY;
        int u;
        for(int i = 0; i < n; i++) {
            if(col[i] != 2 && d[i] < mincost) {
                mincost = d[i];
                u = i;
            }
        }
        if(mincost == INFTY) break;
        col[u] = 2;
        for(int v = 0; v < n; v++) {
            if(col[v] != 2 && M[u][v] != INFTY) {
                if(d[u] + M[u][v] < d[v]) {
                    d[v] = d[u] + M[u][v];
                    p[v] = u;
                    col[v] = 1;
                }
            }
        }
    }

    for(int i = 0; i < n; i++)
        cout << i << " " << (d[i] == INFTY ? -1 : d[i]) << endl;

    return;
}

int main() {
    cin >> n;
    int id, k, v, c;
    for(int i = 0; i < n; i++)
        for(int j = 0; j < n; j++) M[i][j] = INFTY;
    for(int i = 0; i < n; i++) {
        cin >> id >> k;
        for(int j = 0; j < k; j++) {
            cin >> v >> c;
            M[id][v] = c;
        }
    }
    dijkstra(0);
    return 0;
}