Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

var infty = 1000000000

type DirectedGraphNodeID int

type DirectedGraphNode struct {
	key         DirectedGraphNodeID
	adjacents   []*DirectedGraphNode
	costs       []int
	distance    int
	predecessor *DirectedGraphNode
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]*DirectedGraphNode, nNodes)
	for i := 0; i < nNodes; i++ {
		node := DirectedGraphNode{}
		node.key = DirectedGraphNodeID(i)
		node.distance = infty
		graph.nodes[i] = &node
	}
	return &graph
}

type DirectedGraph struct {
	nodes []*DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(i, j DirectedGraphNodeID, cost int) {
	g.nodes[i].adjacents = append(g.nodes[i].adjacents, g.nodes[j])
	g.nodes[i].costs = append(g.nodes[i].costs, cost)
}

func (g *DirectedGraph) print() {
	for i := 0; i < len(g.nodes); i++ {
		node := g.nodes[i]
		key := node.key
		strings := []string{strconv.Itoa(int(key)), strconv.Itoa(node.distance)}
		for j := 0; j < len(node.adjacents); j++ {
			nodeJ := fmt.Sprintf("(%v, %v)", node.adjacents[j].key, node.costs[j])
			strings = append(strings, nodeJ)
		}
		fmt.Printf("%v\n", strings)
	}
}

func (g *DirectedGraph) relaxEdge(l, r *DirectedGraphNode, w int) {
	if r.distance > l.distance+w {
		// fmt.Printf("%v -> %v, %v\n", l.key, r.key, l.distance+w)
		r.distance = l.distance + w
		r.predecessor = l
	}
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	graph := newDirectedGraph(nNodes)

	for i := 0; i < nNodes; i++ {
		iNode := DirectedGraphNodeID(nextInt())
		nAdjacent := nextInt()
		for j := 0; j < nAdjacent; j++ {
			jNode := DirectedGraphNodeID(nextInt())
			cost := nextInt()
			graph.setAdjacency(iNode, jNode, cost)
		}
	}

	graph.nodes[0].distance = 0
	for iNode := 0; iNode < nNodes; iNode++ {
		for iLeft := 0; iLeft < len(graph.nodes); iLeft++ {
			nodeLeft := graph.nodes[iLeft]
			for iRight := 0; iRight < len(nodeLeft.adjacents); iRight++ {
				nodeRight := nodeLeft.adjacents[iRight]
				cost := nodeLeft.costs[iRight]
				graph.relaxEdge(nodeLeft, nodeRight, cost)
			}
		}
	}

	// graph.print()

	for iNode := 0; iNode < len(graph.nodes); iNode++ {
		node := graph.nodes[iNode]
		fmt.Println(node.key, node.distance)
	}
}

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

#define N 101
#define INF 500001 
int n;

int A[N][N];
int color[N];
int d[N];

void dijkstra(int root) {
    d[root] = 0;

    while(true) {
        int added = -1;
        int minw = INF;
        for (int i = 0; i < n; i++) {
            if (color[i] == 0 && d[i] < minw) {
                added = i;
                minw = d[i];
            }
        }

        if (added == -1) {
            break;
        }

        color[added] = 1;
        for (int i = 0; i < n; i++) {
            if (color[i] == 0 && (d[added] + A[added][i]) < d[i]) {
                d[i] = d[added] + A[added][i];
            }
        }
    }
}

int main() {
    cin >> n;

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            A[i][j] = INF;
        }
    }

    int w;
    int node;
    int k;
    int ad;
    for (int i = 0; i < n; i++) {
        color[i] = 0;
        d[i] = INF;

        cin >> node >> k;
        for (int j = 0; j < k; j++) {
            cin >> ad >> w;
            A[i][ad] = w;
        }
    }

    dijkstra(0);

    for (int i = 0; i < n; i++) {
        cout << i << " " << d[i] << endl;
    }

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = 1e16;
const ll mod = 1000000007;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
template<class T> inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template<class T> inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
int ctoi(char c) {
  if (c >= '0' && c <= '9') {
    return c - '0';
  }
  return 0;
}
ll factorial(ll n) {
  if (n == 1) {
    return 1;
  }
  ll ans = factorial(n-1);
  return ans*n;
}
ll gcd(ll a, ll b) {
  if (a < b) {
    ll tmp = a;
    a = b;
    b = tmp;
  }
  ll r = a%b;
  while(r != 0) {
    a = b;
    b = r;
    r = a%b;
  }
  return b;
}
ll lcm(ll a, ll b) {
  return (a/gcd(a, b))*b;
}
bool prime(ll n) {
  if (n == 1) {
    return false;
  } else {
    for (ll i = 2; i <= (ll)pow(n, 0.5); i++) {
      if (n%i == 0) return false;
    }
  }
  return true;
}
ll RepeatSquaring(ll n, ll p, ll m) {
  if (p == 0) return 1;
  if (p%2 == 0) {
    ll t = RepeatSquaring(n, p/2, m);
    return (t*t)%m;
  }
  return (n*RepeatSquaring(n, p-1, m))%m;
}

vector <ll> color(100, 0);
vector <vector <ll>> m(100, vector <ll> (100, -1));
vector <ll> d(100, INF);
vector <ll> p(100, -1);

void dijkstra(ll n) {
  d.at(0) = 0;
  p.at(0) = -1;
  while (true) {
    ll mincost = INF;
    ll u;
    rep(i, n) {
      if (color.at(i) != 2 && d.at(i) < mincost) {
        mincost = d.at(i);
        u = i;
      }
    }
    if (mincost == INF) break;
    color.at(u) = 2;
    rep(i, n) {
      if (color.at(i) != 2 && m.at(u).at(i) != -1) {
        if (d.at(u)+m.at(u).at(i) < d.at(i)) {
          d.at(i) = d.at(u) + m.at(u).at(i);
          p.at(i) = u;
          color.at(i) = 1;
        }
      }
    }
  }
  return;
}

int main() {
  ll n;
  cin >> n;
  rep(i, n) {
    ll u, k;
    cin >> u >> k;
    rep(j, k) {
      ll v, c;
      cin >> v >> c;
      m.at(i).at(v) = c;
    }
  }
  dijkstra(n);
  rep(i, n) {
    cout << i << ' ' << d.at(i) << endl;
  }
}

C++: #include "bits/stdc++.h"
#pragma GCC optimize("Ofast")

// Begin {{{
using namespace std;

#ifndef DEBUG
#define dump(...)
#endif

template <class A, class B> inline bool chmax(A &a, const B &b) { return b > a && (a = b, true); }
template <class A, class B> inline bool chmin(A &a, const B &b) { return b < a && (a = b, true); }

template <class T>
inline vector<T> make_v(const T &initvalue, size_t sz) {
    return vector<T>(sz, initvalue);
}

template <class T, class... Args>
inline auto make_v(const T &initvalue, size_t sz, Args... args) {
    return vector<decltype(make_v<T>(initvalue, args...))>(sz, make_v<T>(initvalue, args...));
}

constexpr int INF = 0x3f3f3f3f;
constexpr int64_t LINF = 0x3f3f3f3f3f3f3f3fLL;
// }}} End

using pii = pair<size_t, size_t>;

vector<pii> G[int(1e2)]; // {node, cost}
size_t N;

vector<size_t> cost(int(1e2), INF);

void dijkstra() {
    priority_queue<pii, vector<pii>, greater<>> que; // {cost, node}
    cost[0] = 0;
    que.emplace(0, 0);

    while (!que.empty()) {
        size_t nowcost = que.top().first;
        size_t nownode = que.top().second;
        que.pop();
        if (cost[nownode] < nowcost) continue;

        for (auto next: G[nownode]) {
            if (chmin(cost[next.first], cost[nownode] + next.second)) {
                que.emplace(cost[next.first], next.first);
            }
        }
    }
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    size_t N; cin >> N;

    for (size_t i = 0; i < N; ++i) {
        size_t u, k; cin >> u >> k;
        for (size_t j = 0; j < k; ++j) {
            size_t v, c; cin >> v >> c;
            G[u].emplace_back(v, c);
        }
    }

    dijkstra();

    for (size_t node = 0; node < N; ++node) {
        cout << node << " " << cost[node] << "\n";
    }

    return 0;
}