Submission #549957

#	Time	Username	Problem	Language	Result	Execution time	Memory
549957		CyberSleeper	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	186 ms	139596 KiB

shoes

#include "shoes.h"

#include <bits/stdc++.h>
#define ll  long long
using namespace std;

int F[200007], sz, N;
void upd(int i, int x){
    i++;
    for(; i<=sz; i+=(i&-i))
        F[i]+=x;
}
int pre(int i){
    i++;
    int ret=0;
    for(; i>0; i-=(i&-i))
        ret+=F[i];
    return ret;
}
long long count_swaps(std::vector<int> s) {
	ll ret=0;
	sz=s.size(), N=sz/2;
	queue<int> cnt[sz+1];
	bool udh[sz];
	for(int i=0; i<sz; i++){
        s[i]+=N;
        cnt[s[i]].push(i);
        upd(i, 1);
	}
	memset(udh, 0, sizeof(udh));
	for(int i=0, j; i<sz; i++){
        if(udh[i])
            continue;
        j=cnt[N-s[i]+N].front();
        cnt[N-s[i]+N].pop();
        cnt[s[i]].pop();
        udh[i]=1, udh[j]=1;
        ret+=pre(j-1);
        if(s[i]<N)
            ret--;
        upd(i, -1);
        upd(j, -1);
        //cout << i << ' ' << ret << endl;
	}
	return ret;
}

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