Submission #736677

#	Time	Username	Problem	Language	Result	Execution time	Memory
736677		bobthebuilder	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	59 ms	13408 KiB

shoes

#include "shoes.h"
#include<bits/stdc++.h>
using namespace std;
#define sz(x) (int)x.size()
#define REP(i,n) for(int i=0;i<n;i++)
#define REP1(i,n) for(int i=1;i<=n;i++)
#define pb push_back
#define lowb(x) (x&(-x))
#define ALL(x) x.begin(),x.end()
#define pii pair<int,int>
#define f first
#define s second
const int maxn=2e5+5;
int pos[maxn];
#define ll long long
vector<int> v[maxn];
int bit[maxn];
void upd(int x,int v){
	while(x<maxn){
		bit[x]+=v;
		x+=lowb(x);
	}
}
int query(int x){
	int ans=0;
	while(x){
		ans+=bit[x];
		x-=lowb(x);
	}
	return ans;
}
long long count_swaps(std::vector<int> s) {
	int n=sz(s)/2;
	int cur=0;
	REP(i,2*n){
		if(s[i]<0){
			v[-s[i]].pb(i);
		}
	}
	REP1(i,n) reverse(ALL(v[i]));
	vector<pii> vv;
	REP(i,2*n){
		if(s[i]>0){
			int z=v[s[i]].back();
			v[s[i]].pop_back();
			int t=i;
			if(z>t) swap(z,t);
			vv.pb({z,t});
		}
	}
	sort(ALL(vv));
	REP(i,n){
		auto x=vv[i];
		if(s[x.f]>0) swap(x.f,x.s);
		pos[x.f]=2*i,pos[x.s]=2*i+1;
	}
	ll ans=0;
	REP(i,2*n){
		ans+=i-query(pos[i]);
		upd(pos[i]+1,1);
	}
	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:34:6: warning: unused variable 'cur' [-Wunused-variable]
   34 |  int cur=0;
      |      ^~~

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