제출 #785487

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
785487		thimote75	메기 농장 (IOI22_fish)	C++17	84 / 100	905 ms	54324 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>;
using nmap  = map<int, num>;

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

template <typename U, typename V>
struct MapCumul {
  map<U, V> s;
  V d;
  MapCumul (map<U, V> &m, V start) {
    V h = start;
    d = start;

    for (const auto &X : m) {
      h += X.second;

      s.insert({ X.first, h });
    }
  }
  V get (U x) {
    auto it = s.upper_bound(x);
    if (it == s.begin()) return d;

    it --;
    return (*it).second;
  }
};

struct LocalResult {
  int N;
  map<int, num> 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.insert({ 0, 0 });
  }

  LocalResult next (nmap &weights) {
    LocalResult next(N);

    MapCumul<int, num> cumul(weights, 0);

    vector<int> positions = { 0 };
    for (const auto &data : weights) {
      if (positions[positions.size()] + 1 != data.first)
        positions.push_back(data.first - 1);
      positions.push_back(data.first);
    }

    if (positions[positions.size() - 1] != N)
      positions.push_back(N);

    auto it_ascend = ascend.begin();
    auto it_descend = descend.begin();
    num opt_ascend = NINF;
    num opt_desc_c = NINF;
    num opt_desc   = NINF;
    for (const auto &descend_data : descend) {
      opt_desc_c = max(
        opt_desc_c,
        descend_data.second + cumul.get(descend_data.first)
      );
    }

    for (int i = 1; i <= positions.size(); i ++) {
      num mx  = NINF;
      int pos = positions[i];
      num cml = cumul.get(pos);

      while (it_ascend != ascend.end() && (*it_ascend).first <= pos) {
        int pas = (*it_ascend).first;
        num vas = (*it_ascend).second;
        opt_ascend = max(opt_ascend, vas - cumul.get(pas));
        it_ascend ++;
      }
      
      mx = max(mx, opt_ascend + cml);

      while (it_descend != descend.end() && (*it_descend).first <= pos) {
        int pds = (*it_descend).first;
        num vds = (*it_descend).second;
        opt_desc = max(opt_desc, vds);
        it_descend ++;
      }

      mx = max(mx, opt_desc + cumul.get(pos));
      mx = max(mx, opt_desc_c);

      next.ascend.insert({ pos, mx });
    }

    it_descend = descend.end(); 
    if (it_descend != descend.begin()) it_descend --;
    bool cdescend = it_descend != descend.end();
    num opt_descpc = NINF;
    for (int i = positions.size() - 1; i >= 0; i --) {
      int pos = positions[i];
      num cml = cumul.get(pos);
      num mx  = NINF;

      while (cdescend && (*it_descend).first >= pos) {
        int pas = (*it_descend).first;
        num pbs = (*it_descend).second;

        opt_descpc = max(
          opt_descpc,
          pbs + cumul.get(pas)
        );

        if (it_descend == descend.begin()) cdescend = false;
        else it_descend --;
      }

      mx = max(mx, opt_descpc - cml);

      next.descend.insert({ pos, mx });
    }

    for (const auto &ascend_data : ascend) {
      int pos = ascend_data.first;
      auto it = next.descend.find(pos);
      num res = ascend_data.second;
      if (it != next.descend.end()) {
        const auto f = *it;
        res = max(res, f.second);
        next.descend.erase(pos);
      }
      next.descend.insert({ pos, res });
    }

    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);

  vector<map<int, num>> grid(N + 1);
  for (int i = 0; i < M; i ++)
    grid[X[i] + 1].insert({ Y[i] + 1, W[i] });

  num res = NINF;
  for (int i = 0; i <= N; i ++) {
    result = result.next( grid[i] );

    if (i == N - 1) {
      for (const auto &u : result.ascend) res = max(res, u.second);
    }
  }
  for (const auto &u : result.descend) res = max(res, u.second);

  return res;
}

컴파일 시 표준 에러 (stderr) 메시지

fish.cpp: In member function 'LocalResult LocalResult::next(nmap&)':
fish.cpp:79:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |     for (int i = 1; i <= positions.size(); i ++) {
      |                     ~~^~~~~~~~~~~~~~~~~~~
fish.cpp:94:13: warning: unused variable 'pds' [-Wunused-variable]
   94 |         int pds = (*it_descend).first;
      |             ^~~
fish.cpp: In function 'ndata cumul(ndata&)':
fish.cpp:152:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  152 |   for (int i = 0; i < arr.size(); i ++)
      |                   ~~^~~~~~~~~~~~

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