Submission #971156

#	Time	Username	Problem	Language	Result	Execution time	Memory
971156		yellowtoad	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	238 ms	283584 KiB

shoes

#include "shoes.h"
#include <iostream>
#include <queue>
#define f first
#define s second
#define int long long
using namespace std;

int p[200010], cnt, nxt, tmp[200010], lll[200010], rrr[200010];
priority_queue<pair<int,int>,vector<pair<int,int>>,greater<pair<int,int>>> ll, rr;
queue<int> l[200010];
queue<int> r[200010];

void merge(int l, int r) {
	if (l >= r) return;
	int mid = (l+r)/2;
	merge(l,mid);
	merge(mid+1,r);
	int x = l, y = mid+1;
	for (int i = l; i <= r; i++) {
		if ((y > r) || ((x <= mid) && (p[x] < p[y]))) tmp[i] = p[x++];
		else {
			cnt += mid-x+1;
			tmp[i] = p[y++];
		}
	}
	for (int i = l; i <= r; i++) p[i] = tmp[i];
}

long long count_swaps(std::vector<signed> a) {
	for (int i = 0; i < a.size(); i++) {
		if (a[i] < 0) {
			ll.push({i,-a[i]});
			l[-a[i]].push(i);
		} else {
			rr.push({i,a[i]});
			r[a[i]].push(i);
		}
	}
	for (int i = 0; i < a.size(); i++) {
		while (lll[ll.top().s]) {
			lll[ll.top().s]--;
			ll.pop();
		}
		while (rrr[rr.top().s]) {
			rrr[rr.top().s]--;
			rr.pop();
		}
		if (i%2 == 0) {
			if (ll.top() < rr.top()) {
				p[ll.top().f] = i;
				nxt = ll.top().s;
				ll.pop();
				l[nxt].pop();
				rrr[nxt]++;
			} else {
				nxt = rr.top().s;
				rr.pop();
				p[l[nxt].front()] = i;
				l[nxt].pop();
				lll[nxt]++;
			}
		} else {
			p[r[nxt].front()] = i;
			r[nxt].pop();
		}
	}
	merge(0,a.size()-1);
	return cnt;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:31:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |  for (int i = 0; i < a.size(); i++) {
      |                  ~~^~~~~~~~~~
shoes.cpp:40:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |  for (int i = 0; i < a.size(); i++) {
      |                  ~~^~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 15 / 15
• Subtask 5: 20 / 20
• Subtask 6: 15 / 15