Submission #1212259

#	Time	Username	Problem	Language	Result	Execution time	Memory
1212259		countless	Nile (IOI24_nile)	C++20	17 / 100	2096 ms	4676 KiB

nile

#include "nile.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);

vector<ll> calculate_costs(vector<int> w, vector<int> a, vector<int> b, vector<int> e) {
    int n = w.size(), q = e.size();

    vector<int> o(n);
    iota(all(o), 0);
    sort(all(o), [&](const int i, const int j) -> bool {
        return w[i] < w[j];
    });

    vector<ll> r(q, 0);

    // for A = 2, B = 1; maximize amount of pairs
    REP(qq, 0, q) {
        int d = e[qq];
        ll ans = n * 2;

        REP(i, 0, n-1) {
            assert(a[o[i]] == 2 and b[o[i]] == 1);

            if (abs(w[o[i]] - w[o[i+1]]) <= d) {
                ans -= 2;
                // cerr << o[i] sp o[i+1] sp w[o[i]] sp w[o[i+1]] << endl;
                i++;
            }
        }

        r[qq] = ans;
        // cerr << endl;
    }

    return r;
}

// Notes
// is it binsearchable? (min max smth)
// is it greedy?
// is it DP?
// if online round: search OEIS, similar topics
// are you using all the information available?

// put observations together
// check for edge cases
// try "dumb" solutions, you're fast enough to rewrite
// clean up the implementation
// keep it simple

// check for overflow
// check for small N
// check for array with same or monotonic a_i

• Subtask 0: 0 / 0
• Subtask 1: 0 / 6
• Subtask 2: 0 / 13
• Subtask 3: 17 / 17
• Subtask 4: 0 / 11
• Subtask 5: 0 / 20
• Subtask 6: 0 / 15
• Subtask 7: 0 / 18