Go: // ダイクストラのアルゴリズム
package main

import (
	"bufio"
	"fmt"
	"log"
	"math"
	"os"
	"strconv"
	"strings"
)

type color int

const (
	white color = iota // 未訪問
	mst                // MSTとして確定
)

// 頂点
type node struct {
	num       int         // 頂点の番号
	weights   map[int]int // 重みMAP
	parent    *node       // MSTへの重み最小の親
	distFromS int         // 始点からの距離
	color     color
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	n := eGetInt(scanner)

	nodes := make([]*node, n)
	for i := 0; i < n; i++ {
		weights := eAtoi((strings.Fields(eGetline(scanner))))
		v := &node{weights[0], make(map[int]int, weights[1]), nil, math.MaxInt32, white}
		for j := 0; j < weights[1]; j++ {
			k := weights[j*2+2] // 相手の頂点名
			w := weights[j*2+3] // 重み
			v.weights[k] = w
		}
		nodes[i] = v
	}

	// 初回はnode[0]がMSTに入るように
	nodes[0].distFromS = 0

	for { // 全部チェックするまで

		// どの頂点を新たにMSTに取り込むか

		var minNode *node
		min := math.MaxInt32
		for _, v := range nodes {
			if v.color == mst {
				continue
			}
			if v.distFromS < min {
				min = v.distFromS
				minNode = v
			}
		}
		if minNode == nil {
			// すべて完了している.
			break
		}

		// MSTに追加する頂点決定
		minNode.color = mst

		// fmt.Printf(">[%v]\n", minNode)
		// MSTに属していない頂点それぞれについて,Startからの最小の重みの距離を更新
		for i, v := range nodes {
			if v.color == mst {
				continue
			}
			w, ok := minNode.weights[i]
			if !ok {
				// minNodeと接してない
				continue
			}

			if minNode.distFromS+w < v.distFromS {
				// minNode経由の距離がもっとも重みが少ないので親を変更
				v.distFromS = minNode.distFromS + w
				v.parent = minNode
				// fmt.Printf("[%v %v]\n", v, minNode)
			}
		}
		// fmt.Printf("<\n")
	}

	for i, v := range nodes {
		fmt.Printf("%d %d\n", i, v.distFromS)
	}
}

func eGetInt(scanner *bufio.Scanner) int {
	t := eAtoi(strings.Fields(eGetline(scanner)))
	return t[0]
}

func eGetline(p *bufio.Scanner) string {
	if !p.Scan() {
		if err := p.Err(); err != nil {
			log.Fatal(err.Error())
		}
		return ""
	}
	return p.Text()
}

func eAtoi(s []string) []int {
	ints := make([]int, len(s))
	var err error
	for i, e := range s {
		ints[i], err = strconv.Atoi(e)
		if err != nil {
			log.Fatal(err.Error())
		}
	}
	return ints
}

C++: #include<bits/stdc++.h>
using namespace std;

#define int long long

int e[111][111],d[111];
int used[111];

signed main(){
  int n;
  cin >> n;
  int INF=1LL<<55LL;
  for(int i=0;i<n;i++)
    for(int j=0;j<n;j++)
      e[i][j] = INF;
  for(int i=0;i<n;i++){
    int u, k;
    cin >> u >> k;
    for(int j=0;j<k;j++){
      int v,c;
      cin>>v>>c;
      e[u][v]=min(e[u][v],c);
    }
  }
  memset(used,0,sizeof(used));
  for(int i=0;i<n;i++) d[i]=INF;
  d[0]=0;
  while(1){
    int u=-1;
    for(int i=0;i<n;i++){
      if(used[i]) continue;
      if(d[i]==INF) continue;
      if(u<0||d[i]<d[u]) u=i;
    }
    if(u<0) break;
    used[u]=1;
    for(int i=0;i<n;i++)
      d[i]=min(d[i],d[u]+e[u][i]);
    
  }
  for(int i=0;i<n;i++) cout<<i<<" "<< d[i] << endl;
  return 0;
}

C++: // ref: p302

using System;

public class SingleSourceShortestPath
{
	const int MAX = 100;
	const int INFTY = Int32.MaxValue;
	const int WHITE = 0;
	const int GRAY = 1;
	const int BLACK = 2;

	static int vertexNum; // ????????° = V
	static int[,] M = new int[MAX,MAX]; // ????????????????¨????????????£??\??????

	static void dijkstra() {
		int minv;
		int[] d = new int[MAX]; // ?§????s????????????v?????§??????????????????????¨????
		int[] color = new int[MAX]; // ?¨??????¶???????????§??¨???

		// ?????????
		for (int i = 0; i < vertexNum; i++) {
			d[i] = INFTY;
			color[i] = WHITE; 
		}

		// ????????????????????????
		d[0] = 0;
		color[0] = GRAY;

		while (true) {
			minv = INFTY;
			int u = -1;
			for (int i = 0; i < vertexNum; 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 < vertexNum; v++) {
				//???????¨?????????????????????????u??¨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 < vertexNum; i++) {
			Console.WriteLine ("{0} {1}", i, (d[i] == INFTY ? -1 : d[i]));
		}
	}
	public static void Main(String[] args) {
		// ????????°
		vertexNum = int.Parse(Console.ReadLine ());
		// ??????????????????
		for (int i = 0; i < vertexNum; i++) {
			for (int j = 0; j < vertexNum; j++) {
				M[i,j] = INFTY;
			}
		}

		int k, c, u, v;
		for (int i = 0; i < vertexNum; i++) {
			string[] readLine = Console.ReadLine().Split(' ');
			int s = 0;
			u = int.Parse(readLine[s]);	// ????????????
			s++;
			k = int.Parse(readLine[s]); 	// ????¬???°
			for (int j = 0; j < k; j++) {
				s++;
				v = int.Parse(readLine[s]);	// ??£??\?????????????????????
				s++;
				c = int.Parse(readLine[s]); // u??¨v????????????????????????
				M[u, v] = c;
			}
		}
		dijkstra ();
	}
}

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 color[MAX], d[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) {
  	      	  minv = d[i];
  	      	  u = 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 << " " << (d[i] == INFTY ? -1 : d[i]) << endl; 
   }
}

int main() {
	cin >> n;
	int u, k, c, v;
	for(int i = 0; i < n; i++) {
		for(int j = 0; j < n; j++) {
			M[i][i] = INFTY;
		}
	}
	
	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 <bits/stdc++.h>
using namespace std;

template<typename T> struct Graph {
  struct Edge { int to; T cost; };
  vector<int> prev;
  vector<vector<Edge>> g;
  Graph(int n) : prev(n, -1), g(n) {}

  void addEdge(int u, int v, T w) {
    g[u].push_back({v, w});
    //g[v].push_back({u, w});
  }
  vector<T> dijkstra(int s) {
    vector<T> dist(g.size(), -1);
    using Node = pair<T, int>;
    priority_queue<Node, vector<Node>, greater<Node>> pq;
    pq.push({dist[s] = 0, s});

    while (!pq.empty()) {
      auto d = pq.top().first;
      auto u = pq.top().second;
      pq.pop();
      if (dist[u] < d) continue;
      for (auto&& v : g[u]) {
        if (dist[v.to] < 0 || dist[v.to] > dist[u] + v.cost) {
          dist[v.to] = dist[u] + v.cost;
          prev[v.to] = u;
          pq.push({dist[v.to], v.to});
        }
      }
    }
    return dist;
  }
  vector<int> getPath(int t) {
    vector<int> path;
    for (; t != -1; t = prev[t]) path.push_back(t);
    reverse(begin(path), end(path));
    return path;
  }
};

int main() {
  int n; cin >> n;
  Graph<int> g(n);
  for (int i = 0; i < n; ++i) {
    int u, k; cin >> u >> k;
    for (int j = 0; j < k; ++j) {
      int v, c; cin >> v >> c;
      g.addEdge(u, v, c);
    }
  }
  vector<int> d = g.dijkstra(0);
  for (int i = 0; i < n; ++i) {
    cout << i << ' ' << d[i] << endl;
  }
  return 0;
}