Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

const BIG_COST = 200000

const (
	ST_NOT_YET = iota
	ST_JOINED
)

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	nNodes := scanInt(sc)

	costs := make([][]int, nNodes)
	graph := make([][]int, nNodes)

	states := make([]int, nNodes)
	costSums := make([]int, nNodes)

	for i := 0; i < nNodes; i++ {
		costs[i] = make([]int, nNodes)
		costSums[i] = BIG_COST
	}

	for i := 0; i < nNodes; i++ {
		u := scanInt(sc)
		k := scanInt(sc)
		graph[u] = make([]int, k)
		for d := 0; d < k; d++ {
			v := scanInt(sc)
			graph[u][d] = v
			costs[u][v] = scanInt(sc)
		}
	}

	costSums[0] = 0
	for {
		minCost := BIG_COST
		var u int

		for i, cost := range costSums {
			if states[i] != ST_JOINED && cost < minCost {
				minCost = cost
				u = i
			}
		}

		if minCost == BIG_COST {
			break
		}

		states[u] = ST_JOINED

		for _, v := range graph[u] {
			cost := minCost + costs[u][v]
			if cost < costSums[v] {
				costSums[v] = cost
			}
		}
	}

	w := bufio.NewWriter(os.Stdout)
	for i, cost := range costSums {
		fmt.Fprintf(w, "%d %d\n", i, cost)
	}
	w.Flush()
}

func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

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

template<typename T>
vector<T> Dijkstra(vector<vector<T>> &G, int s, T inf) {
    vector<T> dist(G.size(),inf);
    vector<bool> used(G.size(),false);

    dist[s] = 0;
    while (true) {
        used[s] = true;
        int u = -1;
        T d = inf;
        for (int v = 0; v < G.size(); ++v) {
            if (used[v]) continue;
            if (dist[v] > dist[s] + G[s][v]) dist[v] = dist[s] + G[s][v];
            if (d > dist[v]) {
                d = dist[v];
                u = v;
            }
        }
        if (u == -1) break;
        s = u;
    }

    return dist;
}

///////////////////////////////////////////////////////////////////////////////

const ll inf = numeric_limits<ll>::max() / 2;

int main() {
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int N; cin >> N;
    vector<vector<ll>> G(N, vector<ll>(N,inf));
    for (int i = 0; i < N; ++i) {
        int u,k; cin >> u >> k;
        for (int j = 0; j < k; ++j) {
            ll v,c; cin >> v >> c;
            G[u][v] = c;
        }
    }

    auto dist = Dijkstra(G,0,inf);
    for (int i = 0; i < N; ++i) {
        cout << i << " " << dist[i] << endl;
    }
}

/*
  verified on 2020/02/04
  http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_12_B&lang=ja
*/

C++: #define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
using namespace std;
const int num = 100, INF = 20000000;
int v[num][num], n, d[num], c[num], p[num];
inline void mini() {
	for (int i = 1; i < n; i++) {
		d[i] = INF;
		c[i] = 0;
	}
	d[0] = 0;
	while (1) {
		int u = -1;
		int minv = INF;
		for (int i = 0; i < n; i++) {
			if (minv > d[i] && c[i] == 0) {
				minv = d[i];
				u = i;
			}
		}
		if (u == -1)break;
		for (int i = 0; i < n; i++) {
			if (c[i] == 0 && v[u][i] != 0) {
				if (d[i] > d[u] + v[u][i]) d[i] = d[u] + v[u][i];
				
			}
		}
		c[u] = 1;
	}

}
int main() {
	cin >> n;
	int u, k, s;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			v[i][j] = 0;
		}
	}
	for (int i = 0; i < n; i++) {
		cin >> u >> k;
		for (int j = 0; j < k; j++) {
			cin >> s;
			cin >> v[u][s];
		}
	}
	mini();
	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 << " " << (d[i]==INFTY?-1: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<iomanip>
#include<algorithm>
#include<bitset>
#include<cctype>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<queue>
#include<vector>
using namespace std;

#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL

#define MAX 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n;
int M[MAX][MAX]; //u??????v??????????????????

void dijkstra() {
	//?§????s???????§???????v?????§??????????????????
	int d[MAX]; memset(d, 0x3f, sizeof(d)); d[0] = 0;
	int color[MAX] = { GRAY };

	while (true) {
		int minv = INF;
		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] != INF) {
				d[v] = min(
					d[v],
					d[u] + M[u][v]
				);
				//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] == INF ? -1 : d[i]) << endl;
	}
}

int main() {
	memset(M, 0x3f, sizeof(M));
	cin >> 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;
			M[u][v] = c;
		}
	}
	dijkstra();
	return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <stack>
#include <vector>
using namespace std;
const int maxx = 1010;
const int INF = 1 << 30;
int n, m[maxx][maxx];
int u, v ,k, c;
int flag[maxx];

void dijkstra() {
	int d[maxx];
	for (int i = 0; i < n; i++) {
		d[i] = INF;
		flag[i] = 0;
	}

	d[0] = 0;
	while (1) {
		int minv = INF;
		u = -1;
		// ???????????????????°???????
		for (int i = 0; i < n; i++) {
			if (minv > d[i] && flag[i] == 0) {
				u = i;
				minv = d[i];
			}
		}

		if (u == -1)
			break;

		// ?????°???????????\S
		flag[u] = 1;

		// ??´??°?????±u?????????V-S???v?????????????°??????¬
		for (int v = 0; v < n; v++) {
			if (flag[v] == 0 && m[u][v] != INF && d[v] > d[u] + m[u][v]) {
				d[v] = d[u] + m[u][v];
			}
		}
	}

	for (int i = 0; i < n; i++)
		printf("%d %d\n", i, d[i] == INF ? -1 : d[i]);
}
int main()
{
	scanf("%d", &n);
	
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			m[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);
			m[u][v] = c;
		}
	}
	dijkstra();
	return 0;
}