Submission #1191608

#	Time	Username	Problem	Language	Result	Execution time	Memory
1191608		countless	Catfish Farm (IOI22_fish)	C++20	100 / 100	200 ms	28228 KiB

fish

#include "fish.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);

ll max_weights(int n, int m, vector<int> x, vector<int> y, vector<int> w) {
    // this will contain at most O(n? + m)
    // time complexity O(n + m log m)
    vector<vector<pair<ll, ll>>> fish(n+2);
    REP(i, 0, m) {
        fish[x[i]+1].push_back({y[i], w[i]});
    }

    // generate prefix sums to each height
    fish[0].push_back({-1, 0});
    REP(i, 1, n+1) {
        fish[i].push_back({-1, 0});
        sort(all(fish[i]));
        REP(j, 1, fish[i].size()) {
            fish[i][j].second += fish[i][j-1].second;
        }
    }
    fish[n+1].push_back({-1, 0});

    // generate indices of possible heights from neighbors
    vector<vector<int>> inds(n+2);
    inds[0].push_back(-1);
    REP(i, 1, n+1) {
        for (auto &f : fish[i-1]) {
            inds[i].push_back(f.first);
        }

        for (auto &f : fish[i+1]) {
            inds[i].push_back(f.first);
        }

        sort(all(inds[i]));
        inds[i].erase(unique(all(inds[i])), inds[i].end());
    }
    inds[n+1].push_back(-1);

    // prefix sum of less than or equal to j
    auto sum = [&](ll i, ll j) {
        return (upper_bound(all(fish[i]), mp(j, LONG_LONG_MAX)) - 1)->second;
    };

    vector<ll> dpu, dpd;
    dpu.push_back(0), dpd.push_back(0);

    // bitonic
    REP(i, 1, n+2) {
        int o = inds[i].size(), p = inds[i-1].size();
        vector<ll> ndpu(o), ndpd(o);
        ll pref = 0, suff = 0;
        int pidx = 0, sidx = p;

        // increasing on this one
        // remove overlap
        // add new
        REP(j, 0, o) {
            while (pidx < p and inds[i-1][pidx] < inds[i][j]) {
                pref = max(pref, dpu[pidx] - sum(i-1, inds[i-1][pidx]));
                pidx++;
            }
            ndpu[j] = max(dpd[0], pref + sum(i-1, inds[i][j]));
        }

        // decreasing on this one
        // add new
        // remove overlap
        for (int j = o-1; j >= 0; j--) {
            while (sidx > 0 and inds[i-1][sidx-1] >= inds[i][j]) {
                sidx--;
                suff = max(suff, max(dpu[sidx], dpd[sidx]) + sum(i, inds[i-1][sidx]));
            }
            ndpd[j] = suff - sum(i, inds[i][j]);
        }

        swap(dpu, ndpu), swap(dpd, ndpd);
    }

    return max(dpu[0], dpd[0]);
}

// signed main() {
//     int n, m; cin >> n >> m;
//     vector<int> x(m), y(m), w(m);
//     REP(i, 0, m) {
//         cin >> x[i] >> y[i] >> w[i];
//     }

//     cout << max_weights(n, m, x, y, w) << endl;
// }

• Subtask 1: 3 / 3
• Subtask 2: 6 / 6
• Subtask 3: 9 / 9
• Subtask 4: 14 / 14
• Subtask 5: 21 / 21
• Subtask 6: 17 / 17
• Subtask 7: 14 / 14
• Subtask 8: 16 / 16