Submission #153493

#	Time	Username	Problem	Language	Result	Execution time	Memory
153493		myungwoo	Arranging Shoes (IOI19_shoes)	C++14	45 / 100	486 ms	276188 KiB

shoes

#include <bits/stdc++.h>
#include "shoes.h"
using namespace std;

#define MAXN 200005
typedef long long lld;

int N;
int A[MAXN], bit[MAXN];
stack <int> L[MAXN], R[MAXN], order;

void add(int n, int v){
	for (;n<=N;n+=n&-n) bit[n] += v;
}
int get(int n)
{
	int ret = 0;
	for (;n;n^=n&-n) ret += bit[n];
	return ret;
}

int move(int a, int b)
{
	// a -> b
	add(a, 1);
	return b-(a-get(a-1));
}

lld proc(vector<int> arr)
{
	N = arr.size();
	for (int i=1;i<=N;i++) A[i] = arr[i-1], bit[i] = 0;
	for (int i=1;i<=N;i++){
		if (A[i] < 0) L[-A[i]].push(i);
		if (A[i] > 0){
			R[A[i]].push(i);
			order.push(A[i]);
		}
	}
	lld total = 0;
	int pos = N;
	while (!order.empty()){
		int t = order.top();
		total += move(R[t].top(), pos);
		total += move(L[t].top(), pos-1);
		order.pop(); R[t].pop(); L[t].pop();
		pos -= 2;
	}
	return total;
}

lld count_swaps(vector<int> arr)
{
	lld ans = proc(arr);
	reverse(arr.begin(), arr.end());
	for (int i=0;i<arr.size();i++) arr[i] = -arr[i];
	ans = min(ans, proc(arr));
	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'lld count_swaps(std::vector<int>)':
shoes.cpp:56:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<arr.size();i++) arr[i] = -arr[i];
               ~^~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 20
• Subtask 3: 20 / 20
• Subtask 4: 15 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 15