Submission #849120

#	Time	Username	Problem	Language	Result	Execution time	Memory
849120		abcvuitunggio	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	46 ms	16476 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
using namespace std;
int a[200001],cnt=1;
long long res,f[200001];
vector <int> pos[200001];
long long count_swaps(vector <int> s){
    for (int i=s.size()-1;i>=0;i--)
        pos[s[i]+s.size()/2].push_back(i);
    for (int i=0;i<s.size();i++)
        if (!a[i]){
            a[i]=cnt;
            int j=pos[s.size()/2-s[i]].back();
            a[j]=cnt+1;
            if (s[i]>0)
                swap(a[i],a[j]);
            pos[s[i]+s.size()/2].pop_back();
            pos[s.size()/2-s[i]].pop_back();
            cnt+=2;
        }
    for (int i=s.size()-1;i>=0;i--){
        for (int j=a[i];j;j-=j&(-j))
            res+=f[j];
        for (int j=a[i];j<=s.size();j+=j&(-j))
            f[j]++;
    }
    return res;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:10:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |     for (int i=0;i<s.size();i++)
      |                  ~^~~~~~~~~
shoes.cpp:24:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |         for (int j=a[i];j<=s.size();j+=j&(-j))
      |                         ~^~~~~~~~~~

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