Submission #379980

#	Time	Username	Problem	Language	Result	Execution time	Memory
379980		Dan4Life	Arranging Shoes (IOI19_shoes)	C++17	0 / 100	5 ms	5248 KiB

shoes

#include <bits/stdc++.h>
#include "shoes.h"
using namespace std;

int Fenwick[200010], n;
void update(int pos, int val) { while(pos<=200000)Fenwick[pos]+=val, pos+=pos&-pos; }
int sum(int x) { int S = 0; while(x)S+=Fenwick[x],x-=x&-x; return S; }
int query(int l, int r) { return sum(r)-sum(l-1); }

long long count_swaps(vector<int> s)
{
    n = (int)s.size()/2;
    vector<pair<int,int> > ord[200010], v;
    for(int i = 0; i < 2*n; i++) ord[abs(s[i])].push_back({s[i],i});
    long long ans = 0;
    for(int i = 1; i<=n; i++)
    {
        sort(ord[i].begin(), ord[i].end());
        for(int j = 0; j < ord[i].size()/2; j++)
        {
            int l = ord[i][j].second, r = ord[i][j+ord[i].size()/2].second;
            if(l>r) ans++, swap(l,r);
            v.push_back({l+1,r+1});
        }
    }
    sort(v.begin(),v.end());
    for(int i = 1; i <= 2*n; i++) update(i,1);
    for(auto u : v)
    {
        int l = u.first, r = u.second;
        ans+=query(l,r), update(l,-1),update(r,-1);
    }
    return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:19:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |         for(int j = 0; j < ord[i].size()/2; j++)
      |                        ~~^~~~~~~~~~~~~~~~~

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