Submission #346612

#	Time	Username	Problem	Language	Result	Execution time	Memory
346612		Pety	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	133 ms	8684 KiB

shoes

#include <bits/stdc++.h>
#include "shoes.h"

using namespace std;

int aib[200002], n;

void update (int x, int val) {
  for (int i = x; i <= n; i += (i & -i))
    aib[i] += val;
}
int query (int x) {
  int sum = 0;
  for (int i = x; i; i -= (i & -i))
    sum += aib[i];
  return sum;
}
int calc (int x) {
  x++;
  return x + query(x);
}

long long count_swaps (vector<int>v) {
  set<pair<int, int>> s;
  n = v.size();
  long long ans = 0;
  for (int i = 0; i < v.size(); i++) {
    int x = v[i];
    auto it = s.lower_bound({-x, 0});
    if (it != s.end() && (*it).first == -x) {
      if (x > 0)
        ans += calc(i) - calc((*it).second) - 1;
      else
        ans += calc(i) - calc((*it).second);
      s.erase(it);
      update(i + 1, -1);
      update((*it).second + 1, 1);
    }
    else
      s.insert({x, i});
  }
  return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:27:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |   for (int i = 0; i < v.size(); i++) {
      |                   ~~^~~~~~~~~~

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