Submission #908666

#	Time	Username	Problem	Language	Result	Execution time	Memory
908666		vjudge1	Catfish Farm (IOI22_fish)	C++17	100 / 100	177 ms	33092 KiB

fish

#include <bits/stdc++.h>
#pragma GCC target ("avx2")
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")

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

typedef long long int ll;
typedef long double ld;
typedef pair<ll, ll> pl;
typedef vector<ll> vl;
#define FD(i, r, l) for(ll i = r; i > (l); --i)

#define K first
#define V second
#define G(x) ll x; cin >> x;
#define GD(x) ld x; cin >> x;
#define GS(s) string s; cin >> s;
#define EX(x) { cout << x << '\n'; exit(0); }
#define A(a) (a).begin(), (a).end()
#define F(i, l, r) for (ll i = l; i < (r); ++i)

enum {
    UP = 0,
    DOWN = 1
};

ll max_weights(int N, int M, std::vector<int> X, std::vector<int> Y,
                      std::vector<int> W) {
  vector<vector<pair<int, int>>> fishes(N);

  F(i, 0, M) fishes[X[i]].push_back(make_pair(Y[i], i));

  ll largest = 0;
  
  vector<pl> up, down; // stores [ypos, dpvalue] of prev state

  vector<vl> dp(M, vl(2, -1e18)); // dp[fish index][type]

  F(x, 0, N) {
    // computes dp[down] for layer 

    if (x > 0) { // w/o this check, we allow placing piers to index -1 which is no bueno
        sort(A(fishes[x]), greater());
      ll max_down = 0, prev = -1e18;
      for (auto [y, i]: fishes[x]) {
        while (down.size() > 0 && down.back().K > y) {
            max_down = max(max_down, down.back().V);
            down.pop_back();
        }

        ll &ret = dp[i][DOWN];
        ret = largest + W[i];
        ret = max(ret, max_down + W[i]);
        ret = max(ret, prev + W[i]);
        prev = max(prev, dp[i][DOWN]);
      }
    }

    if (x >= 1) for (auto [y, i] : fishes[x - 1]) {
        largest = max(largest, dp[i][DOWN]);
    }

    // computes dp[up] for layer; ig implciitly we can already think about largest as the previous dpdown??? 
    {
        sort(A(fishes[x]));
        ll max_up = 0, prev = -1e18;
        for (auto [y, i]: fishes[x]) {
            while (up.size() > 0 && up.back().K < y) {
                max_up = max(max_up, up.back().V);
                up.pop_back();
            }

            ll &ret = dp[i][UP];
            ret = largest + W[i];
            ret = max(ret, max_up + W[i]);
            ret = max(ret, prev + W[i]);
            prev = max(prev, dp[i][UP]);
        }
    }

    if (x >= 1) for (auto [y, i] : fishes[x - 1]) {
        largest = max(largest, dp[i][UP]);
    }

    down.clear();
    for (auto [y, i]: fishes[x]) down.emplace_back(y, dp[i][DOWN]);
    up.clear();
    for (auto [y, i]: fishes[x]) up.emplace_back(y, dp[i][UP]);
    reverse(A(up));
  }

  ll answer = 0;
  F(i, 0, M) {
    answer = max(answer, dp[i][DOWN]);
    if (X[i] + 1 < N) answer = max(answer, dp[i][UP]);
  }

  return answer;
}

• 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