Submission #784722

#	Time	Username	Problem	Language	Result	Execution time	Memory
784722		thimote75	Catfish Farm (IOI22_fish)	C++17	52 / 100	893 ms	2097152 KiB

fish

#include "fish.h"

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

using num   = long long;
using idata = vector<int>;
using igrid = vector<idata>;
using ndata = vector<num>;
using ngrid = vector<ndata>;

const num  INF = 1e18;
const num NINF = -INF;

struct LocalResult {
  int N;
  ndata ascend, descend;
  // ascend[0] = descend[0]
  // ascend[i] => ascend[j] ifof i < j
  // descend[i] => descend[j] ifof i > j

  LocalResult (int _N) {
    N = _N;

    ascend .resize(N + 1, NINF); ascend [0] = 0;
    descend.resize(N + 1, NINF);
  }

  LocalResult next (ndata &cumul) {
    LocalResult next(N);

    num opt_desc_c = NINF;
    for (int i = 0; i <= N; i ++)
      opt_desc_c = max(opt_desc_c, descend[i] + cumul[i]);

    num opt_desc = descend[0];
    num opt_a_mc = ascend[0] - cumul[0];
    for (int i = 1; i <= N; i ++) {
      opt_a_mc = max(opt_a_mc, ascend[i] - cumul[i]);
      num mx = opt_a_mc + cumul[i];

      opt_desc = max(opt_desc, descend[i]);
      mx = max(mx, max(cumul[i] + opt_desc, opt_desc_c));

      next.ascend[i] = mx;
    }

    next.ascend[0] = ascend[0];

    num opt_d_pc = NINF;
    for (int i = N; i >= 0; i --) {
      opt_d_pc = max(opt_d_pc, descend[i] + cumul[i]);

      num mx = opt_d_pc - cumul[i];

      next.descend[i] = max(mx, ascend[i]);
    }

    return next;
  }
};

ndata cumul (ndata &arr) {
  ndata res (arr.size() + 1, 0);

  for (int i = 0; i < arr.size(); i ++)
    res[i + 1] = res[i] + arr[i];
  
  return res;
}

num max_weights(int N, int M, idata X, idata Y, idata W) {
  LocalResult result (N);

  ngrid grid(N + 1, ndata(N));
  for (int i = 0; i < M; i ++)
    grid[X[i] + 1][Y[i]] += W[i];

  for (int i = 0; i <= N; i ++)
    grid[i] = cumul(grid[i]);

  num res = NINF;
  for (int i = 0; i <= N; i ++) {
    result = result.next( grid[i] );
  
    if (i == N - 1) {
      for (num u : result.ascend) res = max(res, u);
    }
  }
  for (num u : result.descend) res = max(res, u);

  return res;
}

Compilation message (stderr)

fish.cpp: In function 'ndata cumul(ndata&)':
fish.cpp:66:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |   for (int i = 0; i < arr.size(); i ++)
      |                   ~~^~~~~~~~~~~~

• Subtask 1: 0 / 3
• Subtask 2: 0 / 6
• Subtask 3: 0 / 9
• Subtask 4: 14 / 14
• Subtask 5: 21 / 21
• Subtask 6: 17 / 17
• Subtask 7: 0 / 14
• Subtask 8: 0 / 16