Submission #835151

#	Time	Username	Problem	Language	Result	Execution time	Memory
835151		kamelfanger83	Arranging Shoes (IOI19_shoes)	C++14	30 / 100	96 ms	15660 KiB

shoes

#include <iostream>
#include <vector>
#include <set>

#include "shoes.h"

using namespace std;

struct Segtree{
    vector<int> cache;
    Segtree (int n){
        cache.resize(4 * n);
    }
    int update(int l, int r, int i, int ui, int ux){
        if(ui < l || r <= ui) return cache[i];
        if (l + 1 == r) return cache[i] = ux;
        int m = l + (r-l)/2;
        return cache[i] = update(l, m, i*2+1, ui, ux) + update(m, r, i*2+2, ui, ux);
    }
    int query(int l, int r, int i, int ql, int qr){
        if (qr <= l || r <= ql) return 0;
        if (ql <= l && r <= qr) return cache[i];
        int m = l + (r-l)/2;
        return query(l, m, i*2+1, ql, qr) + query(m, r, i*2+2, ql, qr);
    }
};

long long count_swaps(vector<int> S){
    set<pair<int, int>> lefts, rights;
    for (int ii = 0; ii < S.size(); ++ii) {
        int i = S[ii];
        if (i < 0) lefts.insert({-i, ii});
        else rights.insert({i, ii});
    }
    int n = S.size();
    Segtree segtree (n);
    long long ans = 0;
    for (int i = 0; i < n / 2; ++i) {
        auto r1 = lefts.begin();
        auto r2 = rights.begin();
        if (lefts.begin()->second > rights.begin()->second) {
            r1 = lefts.lower_bound({r2->first, 0});
        }
        else {
            r2 = rights.lower_bound({r1->first, 0});
        }
        ans += r1->second - segtree.query(0, n, 0, 0, r1->second);
        segtree.update(0, n, 0, r1->second, 1);
        ans += r2->second - segtree.query(0, n, 0, 0, r2->second);
        segtree.update(0, n, 0, r2->second, 1);
        lefts.erase(r1); rights.erase(r2);
    }
    return ans;
}
/*
int main(){
    cout << count_swaps({-2, 2, 2, -2, -2, 2});
}*/

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:30:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |     for (int ii = 0; ii < S.size(); ++ii) {
      |                      ~~~^~~~~~~~~~

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