Submission #657032

#	Time	Username	Problem	Language	Result	Execution time	Memory
657032		600Mihnea	Swapping Cities (APIO20_swap)	C++17	37 / 100	2070 ms	8136 KiB

swap

#include "swap.h"

#include <bits/stdc++.h>

using namespace std;


const int INF = (int) 1e9 + 7;
int n;
int m;
vector<int> t;
vector<int> dim;
vector<int> is_line;
vector<int> is_endpoint;

int root(int a) {
	if (t[a] == a) {
		return t[a];
	} else {
		return root(t[a]);
	}
}

void join(int a, int b, int val) {
	int x = a, y = b;
	a = root(a);
	b = root(b);
	if (a == b) {
		is_line[a] = 0;
		return;
	}
	if (dim[a] < dim[b]) {
		swap(a, b);
		swap(x, y);
	}
	/// dim[a] >= dim[b]
	//if (rng() & 1) {
//		swap(a, b);
//	}
	if (is_line[a] && is_line[b] && is_endpoint[x] && is_endpoint[y]) {
		is_line[a] = 1;
		if (dim[a] > 1) {
			is_endpoint[x] = 0;
		}
		if (dim[b] > 1) {
			is_endpoint[y] = 0;
		}
	} else {
		is_line[a] = 0;
	}
	dim[a] += dim[b];
	t[b] = a;
}

void clr() {
	t.resize(n);
	is_line.resize(n);
	is_endpoint.resize(n);
	dim.resize(n);
	for (int i = 0; i < n; i++) {
		t[i] = i;
		is_line[i] = 1;
		is_endpoint[i] = 1;
		dim[i] = 1;
	}
}

struct Edge {
	int a;
	int b;
	int w;
};

bool operator < (Edge first, Edge second) {
	return first.w < second.w;
}

vector<Edge> edges;

void init(int N, int M, vector<int> U, vector<int> V, vector<int> W) {
	n = N;
	m = M;
	assert((int) U.size() == m);
	assert((int) V.size() == m);
	assert((int) W.size() == m);
	
	edges.clear();
	for (int i = 0; i < m; i++) {
		edges.push_back({U[i], V[i], W[i]});
	}
	sort(edges.begin(), edges.end());
}


int getMinimumFuelCapacity(int x, int y) {
	clr();
	for (auto &edge : edges) {
		int a = edge.a;
		int b = edge.b;
		int w = edge.w;
		join(a, b, w);
		//cout << a << " " << b << " | " << w << " and I care about " << x << " " << y << "\n";
		if (root(x) == root(y) && !is_line[root(x)]) {
			return w; 
		}
	}
	return -1;
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 7
• Subtask 3: 17 / 17
• Subtask 4: 20 / 20
• Subtask 5: 0 / 23
• Subtask 6: 0 / 27