Submission #1204041

#	Time	Username	Problem	Language	Result	Execution time	Memory
1204041		countless	Arranging Shoes (IOI19_shoes)	C++20	100 / 100	216 ms	30284 KiB

shoes

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

typedef long long ll;
typedef long double ld;

const ll MOD = 998244353;
const ll INF = 1e18;
const ld EPS = 1e-12;

#define endl "\n"
#define sp <<" "<<
#define REP(i, a, b) for(ll i = a; i < b; i++)
#define dbg(x) cout << #x << " = " << x << endl
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define fast_io() ios_base::sync_with_stdio(false); cin.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((ll)(x).size())

struct custom_hash {
	static uint64_t splitmix64(uint64_t x) {
		// http://xorshift.di.unimi.it/splitmix64.c
		x += 0x9e3779b97f4a7c15;
		x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
		x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
		return x ^ (x >> 31);
	}

	size_t operator()(uint64_t x) const {
		static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
		return splitmix64(x + FIXED_RANDOM);
	}
};

template <typename Key, typename Value>
using hash_map = unordered_map<Key, Value, custom_hash>;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// uniform_int_distribution<int>(a, b)(rng);
// shuffle(all(a), rng);

// rewriting inversion count

ll merge(vector<int> &a, int l, int m, int r) {
	int n1 = m - l + 1, n2 = r - m;
	vector<int> left(n1), right(n2);
	REP(i, 0, n1) {
		left[i] = a[i+l];
	}

	REP(i, 0, n2) {
		right[i] = a[i+m+1];
	}

	ll res = 0;
	int i = 0, j = 0, k = l;
	while (i < n1 and j < n2) {
		if (left[i] <= right[j]) {
			a[k] = left[i];
			k++, i++;
		} else {
			a[k] = right[j];
			k++, j++;
			res += (n1 - i);
		}
	}

	while (i < n1) {
		a[k] = left[i];
		k++, i++;
	}

	while (j < n2) {
		a[k] = right[j];
		k++, j++;
	}

	return res;
}

ll count(vector<int> &a, int l, int r) {
	ll res = 0;
	if (l < r) {
		int m = (l+r)/2;
		res += count(a, l, m);
		res += count(a, m+1, r);

		res += merge(a, l, m, r);
	}
	return res;
}

ll inversionCount(vector<int> &a) {
	int n = a.size();
	return count(a, 0, n-1);
}

ll count_swaps(vector<int> s) {
	int n = s.size();
	// 2, 1, -1, -2
	// 1, 2, -2, -1
	map<int, vector<int>> pos;
	REP(i, 0, n) {
		pos[s[i]].push_back(i);
	}

	int id = 1;
	for (auto &x : pos) {
		if (x.first > 0) break;

		int m = x.second.size();
		REP(i, 0, m) {
			s[x.second[i]] = -id;
			s[pos[-x.first][i]] = id;
			id++;
		}
	}

	vector<int> dup(n);
	map<int, int> have;
	int curr = 1;
	REP(i, 0, n) {
		if (have[abs(s[i])] != 0) {
			dup[i] = have[abs(s[i])] + (s[i] > 0);
			have[abs(s[i])] = 0;
		} else {
			// cerr << i << endl;
			dup[i] = curr + (s[i] > 0);
			have[abs(s[i])] = curr;
			curr += 2;
		}
	}

	// REP(i, 0, n) {
	// 	cerr << dup[i] << " ";
	// }	cerr << endl;

	// return inversionCount(dup);
	ll ans = inversionCount(dup);
	// assert(ans >= 0 and ans <= (n * (n+1)) / 2);
	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