Submission #145651

#	Time	Username	Problem	Language	Result	Execution time	Memory
145651		Xylofo	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	292 ms	141176 KiB

shoes

#include "shoes.h"

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

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define trav(a, x) for(auto& a : x)
#define all(x) x.begin(), x.end()
#define sz(x) (int)(x).size()
#define eb emplace_back
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;


struct FT {
  vector<ll> s;
  FT(int n) : s(n) {}
  void update(int pos, ll dif) { // a[pos] += dif
    for (; pos < sz(s); pos |= pos + 1) s[pos] += dif;
  }
  ll query(int pos) { // sum of values in [0, pos)
    ll res = 0;
    for (; pos > 0; pos &= pos - 1) res += s[pos-1];
    return res;
  }
};

ll count_swaps(vi s) {
  int n = sz(s)/2;
  vector<deque<int>> nxtR(n+1);
  vector<deque<int>> nxtL(n+1);
  rep(i,0,2*n) {
    if(s[i] > 0) nxtR[s[i]].eb(i);
    else nxtL[-s[i]].eb(i);
  }
  FT ft(2*n+1); // pos delta
  rep(i,1,2*n+1) ft.update(i, 1);
  ll ans = 0;

  vi alive(2*n, 1);

  auto mv = [&](int target, int i, int q) {
    int pos = ft.query(i+1);
    ans += pos - target;
    ft.update(0, 1);
    ft.update(i+1, -1);

    alive[nxtL[q].front()] = 0;
    alive[nxtR[q].front()] = 0;
    nxtL[q].pop_front();
    nxtR[q].pop_front();
  };

  int j = 0;
  rep(i,0,n) {
    while(alive[j] == 0) ++j;
    int q = abs(s[j]);
    if (s[j] < 0) // left shoe
      mv(2*i+1, nxtR[q].front(), q);
    if (s[j] > 0) // right shoe
      mv(2*i, nxtL[q].front(), q);
  }
  return ans;
}

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