Submission #1306447

#	Time	Username	Problem	Language	Result	Execution time	Memory
1306447		baodat	Arranging Shoes (IOI19_shoes)	C++20	10 / 100	1 ms	352 KiB

shoes

#include <bits/stdc++.h>
using namespace std;
#define ll long long 
#define FOR(i, l, r) for(int i = l; i <= r; i++)
#define FORD(i, l, r) for(int i = l; i >= r; i--)
#define all(x) (x).begin(), (x).end()
struct BIT{
  int n;
  vector<int> bit;
  BIT(int __n = 0){
    init(__n);
  }
  void init(int __n = 0){
    n = __n;
    bit.assign(n + 5, 0);
  }
  void update(int i, int v){
    ++i;
    while(i <= n){
      bit[i] += v;
      i += i &-i;
    }
  }
  int query(int i){
    ++i;
    int ans = 0;
    while(i > 0){
      ans += bit[i];
      i -= i &-i;
    }
    return ans;
  }
  int query(int l, int r){
    return query(r) - query(l - 1);
  }
};
ll count_swaps(vector<int> a){
  int n = a.size();
  int maxi = *max_element(all(a));
  BIT bit(n + 1);
  vector<int> pos(n + 1, 0), match(n + 1, -1), last(maxi + 1, -1);
  FOR(i, 0, n - 1){
    int x = abs(a[i]);
    if(last[x] == -1) last[x] = i;
    else{
      match[i] = last[x];
      match[last[x]] = i;
    }
  }
  //FOR(i, 0, n - 1) cout << i << ": " << match[i] << " ";
  ll ans = 0;
  FOR(i, 0, n - 1) bit.update(i, 1);
  vector<bool> used(n, false);
  FOR(i, 0, n - 1){
    if(used[i]) continue;
    int j = match[i];
    if(i > j) continue;
    ans += bit.query(i + 1, j - 1);
    bit.update(i, -1);
    bit.update(j, -1);
    if(a[i] > 0) ++ans;
    used[i] = used[j] = true;
  }
  return ans;
}

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