Submission #981910

#	Time	Username	Problem	Language	Result	Execution time	Memory
981910		vjudge1	Swapping Cities (APIO20_swap)	C++17	50 / 100	2045 ms	31728 KiB

swap

#include "swap.h"
#include <bits/stdc++.h>
#include <vector>
using namespace std;
long long n, m, i, j, sz[200001], p[200001], d[200001], mx[200001], szm[200001], kek[200001];
multiset<pair<long long, long long>> ms;
int mxx;
bool st1, st2;
vector<pair<long long, long long>> g[200001];
vector<pair<long long, pair<long long, long long>>> gg;

long long get(long long x) {
	return x == p[x] ? x : p[x] = get(p[x]);
}

void merge(long long xx, long long yy) {
	long long x = get(xx), y = get(yy);
	mx[x] = max({mx[x], d[x], d[xx]});
	mx[y] = max({mx[y], d[y], d[yy]});
	mx[x] = max(mx[x], mx[y]);
	mx[y] = max(mx[y], mx[x]);
	szm[x]++;
	if (x == y) return;
	if (sz[x] < sz[y]) swap(x, y);
	p[y] = x;
	sz[x] += sz[y];
	szm[x] += szm[y];
	mx[x] = max(mx[x], mx[y]);
	mx[y] = max(mx[y], mx[x]);
}

void init(int N, int M,
          std::vector<int> U, std::vector<int> V, std::vector<int> W) {
	n = N, m = M;
	st2 = 1;
	for (long long i = 0; i < M; i++) {
		g[U[i]].push_back({V[i], W[i]});
		g[V[i]].push_back({U[i], W[i]});
		if (U[i]) {
			st2 = 0;
		}
		gg.push_back({W[i], {U[i], V[i]}});
		kek[V[i]] = W[i];
		mxx = max(mxx, W[i]);
	}
	if (st2) {
		for (long long i = 0; i < N; i++) ms.insert({kek[i], i});
	}
	st1 = 1;
	for (long long i = 0; i < N; i++) {
		if (g[i].size() > 2) st1 = 0;
	}
	sort(gg.begin(), gg.end());
}

bool check(long long md, long long x, long long y) {
	if (md < 0 || md >= gg.size()) return 0;
	for (long long i = 0; i < n; i++) sz[i] = 1, p[i] = i, d[i] = mx[i] = szm[i] = 0;
	for (long long i = 0; i <= md; i++) {
		d[gg[i].second.first]++;
		d[gg[i].second.second]++;
		merge(gg[i].second.first, gg[i].second.second);
	}
	if (get(x) != get(y)) return 0;
	if (mx[get(x)] <= 2 && szm[get(x)] < sz[get(x)]) return 0;
	return 1;
}

int getMinimumFuelCapacity(int X, int Y) {
	if (st1) {
		if (n == m) return mxx;
		return -1;
	}
	if (st2) {
		if (ms.size() > 2) {
			ms.erase({kek[X], X});
			ms.erase({kek[Y], Y});
			long long ans = max({kek[X], kek[Y], (gg[2].first)});
			ms.insert({kek[X], X});
			ms.insert({kek[Y], Y});
			return ans;
		}
		return -1;
	}
	long long l = 0, r = (int)gg.size(), md, ans = 0;
	while (l <= r) {
		md = (l + r) / 2;
		if (check(md, X, Y)) ans = md, r = md - 1;
		else l = md + 1;
	}
	if (!check(ans, X, Y)) return -1;
  return gg[ans].first;
}

Compilation message (stderr)

swap.cpp: In function 'bool check(long long int, long long int, long long int)':
swap.cpp:57:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, std::pair<long long int, long long int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   57 |  if (md < 0 || md >= gg.size()) return 0;
      |                ~~~^~~~~~~~~~~~

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