Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
type Node struct {
	cost int
	done bool
}

type Edge struct {
	to, cost int
}

const INF = 1 << 60

func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	nodes := make([]Node, N)
	for i := 0; i < N; i++ {
		nodes[i].cost = INF
	}
	E := make([][]Edge, N)
	for i := 0; i < N; i++ {
		id, k := sc.nextInt(), sc.nextInt()
		for j := 0; j < k; j++ {
			to, cost := sc.nextInt(), sc.nextInt()
			E[id] = append(E[id], Edge{to, cost})
		}
	}
	nodes[0].cost = 0
	for {
		cur := 0
		minCost := INF
		for i := 0; i < N; i++ {
			n := nodes[i]
			if !n.done && n.cost < minCost {
				cur = i
				minCost = n.cost
			}
		}
		if minCost == INF {
			break
		}
		nodes[cur].done = true
		for i := 0; i < len(E[cur]); i++ {
			to, cost := E[cur][i].to, E[cur][i].cost+nodes[cur].cost
			if !nodes[to].done && cost < nodes[to].cost {
				nodes[to].cost = cost
			}
		}
	}

	for i := 0; i < N; i++ {
		fmt.Fprintln(wtr, i, nodes[i].cost)
	}
	wtr.Flush()
}

C++: #include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wconversion"

using namespace std;

#define FOR(i, a, b) for (ll i = (a); i < (b); i++)
#define RFOR(i, a, b) for (ll i = (b)-1; i >= (a); i--)
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define rep1(i, n) for (ll i = 1; i <= (n); i++)
#define rrep(i, n) for (ll i = (n)-1; i >= 0; i--)

#define pb push_back
#define mp make_pair
#define fst first
#define snd second
#define show(x) cout << #x << " = " << x << endl
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define pii pair<int, int>

namespace is_stl_container_impl
{
template <typename T>
struct is_stl_container : false_type {
};
template <typename T, size_t N>
struct is_stl_container<array<T, N>> : true_type {
};
template <typename... Args>
struct is_stl_container<vector<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<deque<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<list<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<forward_list<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<set<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<multiset<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<map<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<multimap<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<unordered_set<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<unordered_multiset<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<unordered_map<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<unordered_multimap<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<stack<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<queue<Args...>> : true_type {
};
template <typename... Args>
struct is_stl_container<priority_queue<Args...>> : true_type {
};
}  // namespace is_stl_container_impl

//type trait to utilize the implementation type traits as well as decay the type
template <typename T>
struct is_stl_container {
    static constexpr bool const value = is_stl_container_impl::is_stl_container<decay_t<T>>::value;
};

template <typename T>
typename enable_if<is_stl_container<T>::value, ostream&>::type operator<<(ostream& os, const T& container)
{
    os << "[";
    for (const auto& p : container) {
        os << p << ",";
    }
    os << "]";
    return os;
}

template <typename S, typename T>
ostream& operator<<(ostream& os, const pair<S, T>& p)
{
    os << "(" << p.first << "," << p.second
       << ")";
    return os;
}

using ll = long long;
constexpr ll MOD = 1000000007;

template <typename T>
constexpr T INF = numeric_limits<T>::max() / 100;

struct DGraph {
    using T = ll;
    DGraph(const int v) : V{v}
    {
        edge.resize(v);
        rev_edge.resize(v);
    }
    struct Edge {
        Edge(const int from, const int to, const T cost) : from{from}, to{to}, cost{cost} {}
        const int from;
        const int to;
        const T cost;
        bool operator<(const Edge& e) const
        {
            return cost != e.cost ? cost < e.cost : to < e.to;
        }
    };
    void addEdge(const int from, const int to, const T cost)
    {
        edge[from].push_back(Edge{from, to, cost});
        rev_edge[to].push_back(Edge(to, from, cost));
    }
    vector<vector<Edge>> edge;
    vector<vector<Edge>> rev_edge;
    const int V;
};

void Dijkstra(const DGraph& g, const int s, vector<DGraph::T>& d)
{
    using T = DGraph::T;
    assert(s < g.V);
    assert(d.size() == g.V);
    using P = pair<T, int>;
    priority_queue<P, vector<P>, greater<P>> q;
    for (int i = 0; i < g.V; i++) {
        d[i] = INF<T>;
    }
    d[s] = 0;
    q.push(make_pair(0, s));
    while (not q.empty()) {
        const P& p = q.top();
        const T cost = p.first;
        const int v = p.second;
        q.pop();
        if (d[v] < cost) {
            continue;
        }
        for (const auto& e : g.edge[v]) {
            if (d[e.to] > d[v] + e.cost) {
                d[e.to] = d[v] + e.cost;
                q.push(make_pair(d[e.to], e.to));
            }
        }
    }
}

int main()
{
    int V, E, r;
    cin >> V >> E >> r;
    DGraph g{V};
    for (int i = 0; i < E; i++) {
        int s, t;
        ll c;
        cin >> s >> t >> c;
        g.addEdge(s, t, c);
    }
    vector<long long> d(V);
    Dijkstra(g, r, d);
    for (int i = 0; i < V; i++) {
        if (d[i] != INF<ll>) {
            cout << d[i] << endl;
        } else {
            cout << "INF" << endl;
        }
    }
    return 0;
}