Submission #244830

#	Time	Username	Problem	Language	Result	Execution time	Memory
244830		crossing0ver	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	175 ms	20492 KiB

shoes

#include<bits/stdc++.h>
#define ll long long 
#ifndef local
#include "shoes.h"
#endif
using namespace std;
const int MAXN = 2e5+5;
int BIT[MAXN];
void add(int pos,int val) {
	for (pos++;pos < MAXN;pos+=pos&-pos)
		BIT[pos]+=val;
}
int get(int pos) {
	int s = 0;
	for (pos++;pos;pos-=pos&-pos)
		s += BIT[pos];
	return s;
}
ll count_swaps(vector<int> a) {
	int n = a.size();
	ll ans = 0;
	vector< vector<vector<int>> > v(2,vector< vector<int> >(n+1));
	for (int i = 0;i < n; i++) {
		if (a[i] < 0) v[1][-a[i]].push_back(i);
		else v[0][a[i]].push_back(i);
		add(i,1);
	}
	vector<int> vis(n,1);
	for (int i = 1; i <= n; i++)
	for (int t = 0; t < 2; t++)
		reverse(v[t][i].begin(),v[t][i].end());
	for (int i = 0; i < n;i++) {
		if (vis[i] == 0) continue;
		int x = a[i];
		int val = abs(x);
		int t = (x < 0 ? 0 : 1);
		int ps = v[t][val].back();
		vis[i] = 0;
		v[t][val].pop_back();
		v[!t][val].pop_back();
		if (i+1 < ps) ans+= get(ps-1) - get(i);
		add(ps,-1);
		add(i,-1);
		if (t == 1) ans++;
		vis[ps] = 0;
	}
	return ans;	
}
#ifdef local
main() {
	int n; cin >> n;
	vector<int> v(n);
	for (int i = 0;i < n; i++) cin >> v[i];
	cout << count_swaps(v);
}
#endif

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