Submission #205043

#	Time	Username	Problem	Language	Result	Execution time	Memory
205043		ADJA	Arranging Shoes (IOI19_shoes)	C++14	100 / 100	661 ms	150520 KiB

shoes

#include "shoes.h"

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <bitset>
#include <cmath>
#include <queue>
#include <stack>
#include <string>

#define sz(x) (int) x.size()
#define all(x) x.begin(), x.end()

using namespace std;

const int MAXN = 2 * 105000;

class Fenwick {
private:
  vector <long long> f;
public:
  void init(int n) {
    f.assign(n, 0);
  }
  void update(int pos, int delta) {
    for (; pos < sz(f); pos = (pos | (pos + 1))) {
      f[pos] += delta;
    }
  }
  long long sum(int pos) {
    long long res = 0;
    for (; pos >= 0; pos = (pos & (pos + 1)) - 1) {
      res += f[pos];
    }
    return res;
  }
  long long sum(int l, int r) {
    return sum(r) - sum(l - 1);
  }
};

int n;
vector<int> s;
map <int, queue<int>> mp;
int a[MAXN];
Fenwick f;

long long solveSameSize() {
  set<int> stA, stB;
  for (int i = 0; i < n; i++) {
    if (s[i] < 0) {
      stA.insert(i);
    } else {
      stB.insert(i);
    }
  }

  long long result = 0;
  for (int i = 0; i < n; i++) {
    if (i % 2 == 0) {
      int mn = *stA.begin();
      stA.erase(stA.begin());
      result += max(0, mn - i);
    } else {
      int mn = *stB.begin();
      stB.erase(stB.begin());
      result += max(0, mn - i);
    }
  }

  return result;
}

long long solveFour() {
  long long result = 0;

  for (int i = n / 2 - 1; i >= 0; i--) {
    result += i;
  }

  return result;
}

long long solveSmall() {
  long long result = 0;
  vector<int> left, right;

  for (int i = 0; i < n; i += 2) {
    int best = -1, bestVal = 0;

    left.assign(n + 1, -1);
    right.assign(n + 1, -1);

    for (int j = i; j < n; j++) {
      int sz = abs(s[j]);
      if (s[j] < 0) {
        if (left[sz] == -1) {
          left[sz] = j;
        }
      } else {
        if (right[sz] == -1) {
          right[sz] = j;
        }
      }
    }

    for (int j = 1; j <= n; j++) {
      if (left[j] == -1 || right[j] == -1) {
        continue;
      }
      int cur = 0;
      if (left[j] < right[j]) {
        cur = left[j] - i + (right[j] - (i + 1));
      } else {
        cur = left[j] - i + (right[j] - i);
      }
      if (best == -1 || cur < bestVal) {
        best = j;
        bestVal = cur;
      }
    }

    result += bestVal;
    for (int j = min(left[best], right[best]); j > i; j--) {
      s[j] = s[j - 1];
    }
    for (int j = max(left[best], right[best]); j > i; j--) {
      s[j] = s[j - 1];
    }
    s[i] = -best;
    s[i + 1] = best;

    /* cerr << result << endl;
    for (int j = 0; j < n; j++) {
      cerr << s[j] << " ";
    }
    cerr << endl; */
  }

  return result;
}

long long count_swaps(std::vector<int> S) {
  s = S;
  n = sz(s);

  f.init(n);

  for (int i = 0; i < n; i++) {
    mp[s[i]].push(i);
    a[i] = 1;
    f.update(i, 1);
  }

  long long ans = 0;
  for (int i = 0; i < n; i++) {
    if (a[i] == 0) {
      continue;
    }
    int mnPos = mp[-s[i]].front();
    // cerr << i << " " << mnPos << endl;

    int curNum = f.sum(0, mnPos);  
    if (s[i] < 0) {
      ans += curNum - 2;
    } else {
      ans += curNum - 1;
    }

    mp[-s[i]].pop();
    mp[s[i]].pop();
    a[mnPos]--;
    f.update(mnPos, -1);
    a[i]--;
    f.update(i, -1);
  }

  return ans;

  // int sz = abs(s[0]);
  // bool sameSize = true;
  // for (int i = 0; i < n; i++) {
  //   if (abs(s[i]) != sz) {
  //     sameSize = false;
  //   }
  // }
  // if (sameSize) {
  //   return solveSameSize();
  // }

  // bool ok = true;
  // for (int i = 0; i < n / 2; i++) {
  //   if (s[i] > 0 || abs(s[i]) != abs(s[i + n / 2])) {
  //     ok = false;
  //   }
  // }
  // for (int i = n / 2; i < n; i++) {
  //   if (s[i] < 0) {
  //     ok = false;
  //   }
  // }
  // if (ok) {
  //   return solveFour();
  // }

  // return solveSmall();
}

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