Submission #225735

#	Time	Username	Problem	Language	Result	Execution time	Memory
225735		grt	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	133 ms	16504 KiB

shoes

#include <bits/stdc++.h>
#define PB push_back
#define ST first
#define ND second
#define _ ios_base::sync_with_stdio(0); cin.tie(0);
//mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

using namespace std;

using ll = long long;
using pi = pair<int,int>;
using vi = vector<int>;

const int nax = 100*1000+10;
int T[(1<<19)],R;
vi lft[nax],rght[nax];
int nxt[2*nax];

void update(int a,int x) {
	a+=R;
	T[a] += x;
	while(a>1) {
		a/=2;
		T[a] = T[2*a] + T[2*a+1];
	}
}

int query(int a,int b) {
	a+=R; b+=R;
	if(a > b) return 0;
	int w = T[a] + (a!=b?T[b]:0);
	while(a/2!=b/2) {
		if(a%2==0) w+=T[a+1];
		if(b%2==1) w+=T[b-1];
		a/=2; b/=2;
	}
	return w;
}

ll count_swaps(vector<int> t) {
	int n = t.size();
	R = 1;
	ll ans = 0;
	while(R < n) R*=2;
	for(int i = 0; i < n; ++i) {
		if(t[i] < 0) {
			lft[-t[i]].PB(i);
		} else {
			rght[t[i]].PB(i);
		}
	}
	for(int i = 1; i <= n/2; ++i) {
		for(int j = 0; j < (int)lft[i].size(); ++j) {
			ans += (lft[i][j] > rght[i][j]);
			nxt[min(lft[i][j],rght[i][j])] = max(lft[i][j],rght[i][j]);
		}
	} 
	for(int i = 0; i < n; ++i) {
		if(nxt[i] == 0) continue;
		ans += nxt[i] - i - 1 - query(i+1,nxt[i]-1);
		update(nxt[i],1);
	}
	return ans;
}

//~ int main() {
	//~ cout << count_swaps({2,1,-1,-2});
//~ }

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