Go: package main

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

const (
	white int = iota
	gray
	black
)

type node struct {
	id     int
	parent int
	edge   []int
	weight []int
	color  int
}

type graph struct {
	nodes    []node
	distance []int
}

var infty = 1 << 32
var null = -1

func constructgraph() *graph {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	n := nextInt(sc)

	g := &graph{make([]node, n), make([]int, n)}

	for i := 0; i < n; i++ {
		id := nextInt(sc)
		edges := nextInt(sc)
		n := node{}
		n.id = id
		n.edge = make([]int, edges)
		n.weight = make([]int, edges)
		n.color = white
		for j := 0; j < edges; j++ {
			to := nextInt(sc)
			w := nextInt(sc)
			n.edge[j] = to
			n.weight[j] = w
		}
		g.nodes[id] = n
	}
	return g
}

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

func (g *graph) preparedijkstra(s int) {
	for i := 0; i < len(g.nodes); i++ {
		g.nodes[i].color = white
		g.nodes[i].parent = null
		g.distance[i] = infty
	}
	g.distance[s] = 0
}

func (g *graph) dijkstra(s int) []int {
	g.preparedijkstra(s)

	for {
		var u int
		mincost := infty
		for i, d := range g.distance {
			if g.nodes[i].color != black && mincost > d {
				mincost = d
				u = i
			}
		}

		if mincost == infty {
			break
		}

		g.nodes[u].color = black

		for i, e := range g.nodes[u].edge {
			if g.nodes[e].color != black {
				if g.distance[e] > g.distance[u]+g.nodes[u].weight[i] {
					g.distance[e] = g.distance[u] + g.nodes[u].weight[i]
					g.nodes[e].parent = u
					g.nodes[e].color = gray
				}
			}
		}
	}
	return g.distance
}

func printShortestPath(d []int) {
	for i, v := range d {
		fmt.Printf("%d %d\n", i, v)
	}
}

func main() {
	g := constructgraph()
	d := g.dijkstra(0)
	printShortestPath(d)
}

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;
}