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++: //#define LOCAL

#include<cstdio>
#include<algorithm>
#include<cstring>

using namespace std;

#define rep(a, b) for(int i = a; i <= b; i++)
#define mst(a) memset(a, 0, sizeof(a))

const int MAX = 1e2 + 10;
const int INF = 0x3f3f3f3f;

int g[MAX][MAX];
int dist[MAX];
bool vis[MAX];

void init(int n)
{
	rep(0, n - 1)
	{
		dist[i] = INF;
		for(int j = 0; j < n; j++)
			g[i][j] = INF;
	}
	mst(vis);
	return;
}

void dijkstra(int n)
{
	rep(0, n - 1)
		dist[i] = INF;
	dist[0] = 0;
	rep(0, n - 1)
	{
		int mnidx = -1, mndist = INF;
		for(int j = 0; j < n; j++)
			if(!vis[j] && dist[j] < mndist)
				mnidx = j, mndist = dist[j];
		vis[mnidx] = true;
		for(int j = 0; j < n; j++)
			if(!vis[j])
				dist[j] = min(dist[j], dist[mnidx] + g[mnidx][j]);
	}
	return;
}

int main()
{

#ifdef LOCAL
	freopen("in.txt", "r", stdin);
#endif

	int n;
	while(~scanf("%d", &n))
	{
		init(n);
		rep(0, n - 1)
		{
			int u, v, w, num;
			scanf("%d%d", &u, &num);
			while(num--)
			{
				scanf("%d%d", &v, &w);
				g[u][v] = w;
			}
		}

		dijkstra(n);

		rep(0, n - 1)
			printf("%d %d\n", i, dist[i]);
	}
	return 0;
}

C++: #include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <cmath>
#include <cstdlib>
using namespace std;
#define Test
const int MAX = 110000;
const int INF = 10000000;
vector<pair<int, int> > G[MAX];
int n;
int dis[MAX];
int vis[MAX];

void dij(int p) {
    for (int i = 0; i < n; i++) dis[i] = INF;
    memset(vis, false, sizeof(vis));
    dis[p] = 0;
    priority_queue<pair<int, int>, vector<pair<int,int>>, greater<pair<int,int>>> pq;
    pq.push(make_pair(0, p));
    while (!pq.empty()) {
        pair<int, int> pr = pq.top();
        pq.pop();
        int point = pr.second;
        if (vis[point]) continue;
        dis[point] = pr.first;
        vis[point] = true;
        for (int i = 0; i < G[point].size(); i++) {
            int pt = G[point][i].second;
            int v = G[point][i].first;
            if (!vis[pt] && dis[pt] > dis[point]+v) {
                dis[pt] = dis[point] + v;
                pq.push(make_pair(dis[pt], pt));
            }
        }
    }
}

int main() {
    //freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
    scanf("%d", &n);
    for (int i = 0; i < n; i++) {
        int p, k;
        scanf("%d %d", &p, &k);
        while (k--) {
            int v, c;
            scanf("%d %d", &v, &c);
            G[p].push_back(make_pair(c, v));
        }
    }
    dij(0);
    for (int i = 0; i < n; i++) {
        printf("%d %d\n", i, dis[i]);
    }
    return 0;
}

C++: #include <cstdio>
#include <iostream>
using namespace std;

static const int MAX_NUM   = 101;
static const int NIL       = 100001;
static const int NO_VISIT  = 0;
static const int NOW_VISIT = 1;
static const int END_VISIT = 2;

void SSSP(int *pMatrix, int num)
{
    int i;
    int mincost;
    int target;
    int lcost[MAX_NUM];
    int parent[MAX_NUM];
    int state[MAX_NUM];
    int *pList;

    for (i = 0; i < num; i++) {
        lcost[i]  = NIL;
        parent[i] = -1;
        state[i]  = NO_VISIT;
    }

    lcost[0]  = 0;
    parent[0] = 0;
    state[0]  = NOW_VISIT;

    for (;;) {
        mincost   = NIL;
        for (i = 0; i < num; i++) {
            if ((lcost[i] < mincost) && (state[i] != END_VISIT)) {
                target = i;
                mincost = lcost[i];
            }
        }
        if (mincost == NIL) {
            break;
        }

        state[target] = END_VISIT;
        pList = pMatrix + MAX_NUM * target;
        for (i = 0; i < num; i++) {
            if ((*(pList + i) + lcost[target]) < lcost[i]) {
                lcost[i]  = *(pList + i) + lcost[target];
                state[i]  = NOW_VISIT;
                parent[i] = target;
            }
        }
    }

    for (i = 0; i < num; i++) {
        printf("%d %d\n", i, lcost[i]);
    }

    return;
}

int main(void)
{
    int i, j;
    int num;
    int tmp;
    int target, elem, cost;
    int matrix[MAX_NUM][MAX_NUM];

    scanf("%d", &num);
    for (i = 0; i < num; i++) {
        for (j = 0; j < num; j++) {
            matrix[i][j] = NIL;
        }
    }

    for (i = 0; i < num; i++) {
        scanf("%d %d", &target, &tmp);
        for (j = 0; j < tmp; j++) {
            scanf("%d %d", &elem, &cost);
            matrix[target][elem] = cost;
        }
    }

    SSSP(&matrix[0][0], num);

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
static const int INF   = (1 << 21);
static const int WHITE = 0;
static const int GRAY  = 1;
static const int BLACK = 2;
static const int NIL   = -1;
static const int MAX   = 100;

int n;
vector<vector<int>> M(MAX, vector<int>(MAX, NIL));

void dijstra(int s) {
  vector<int> color(n, WHITE);
  vector<int> d(n, INF);
  vector<int> p(n);
  d[s] = 0;
  p[s] = NIL;

  while (true) {
    int u       = 0;
    int mincost = INF;
    for (int i = 0; i < n; i++) {
      if (color[i] != BLACK && d[i] < mincost) {
        mincost = d[i];
        u       = i;
      }
    }
    if (mincost == INF) { break; }

    color[u] = BLACK;

    for (int v = 0; v < n; v++) {
      if (color[v] != BLACK && M[u][v] != NIL) {
        if (d[u] + M[u][v] < d[v]) {
          d[v]     = d[u] + M[u][v];
          p[v]     = u;
          color[v] = GRAY;
        }
      }
    }
  }
  int res = 0;
  for (int i = 0; i < n; i++) {
    cout << i << " " << d[i] << endl;
  }
}

int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    int id, k;
    cin >> id >> k;
    for (int j = 0; j < k * 2; j += 2) {
      int v, c;
      cin >> v >> c;
      M[id][v] = c;
    }
  }
  dijstra(0);
}