Submission #1027990

#	Time	Username	Problem	Language	Result	Execution time	Memory
1027990		NeroZein	Catfish Farm (IOI22_fish)	C++17	0 / 100	1041 ms	51996 KiB

fish

#include "fish.h"
#include <bits/stdc++.h>

using namespace std;

int n; 
vector<vector<long long>> dp;
vector<vector<long long>> nxt;
vector<vector<long long>> pre;
vector<vector<pair<int, int>>> in_col;

long long bt(int col, bool f) {
  if (col == n) {
    return 0;
  }
  long long& ret = dp[col][f];
  if (ret != -1) {
    return ret; 
  }
  ret = 0; 
  int sz = in_col[col].size();
  if (!f) {//I'm not taking from the one behind me -> the one in front of me is bigger than me & the one behind me is not a full tower so he's taking from me
    long long s = 0;
    for (int i = 0; i < sz - 1; ++i) {//take from the next one and give the previous one
      long long w = s; 
      if (col > 0) {
        w += pre[col][i];
      }
      ret = max(ret, bt(col + 1, 0) + w); 
      s -= in_col[col][i].second;
    }
    if (col < n - 1) {
      s = nxt[col][sz - 1]; 
    }
    if (col > 0) {
      s += pre[col][sz - 1];
    }
    ret = max(ret, bt(col + 1, 1) + s);//end the sequence. (build a full tower)
  } else {//I'm taking from the one behind me -> the one next either takes from me or I don't build anything (subtract me and add the guy next)
    long long s = 0; 
    for (int i = 0; i < sz; ++i) {
      long long w = s; 
      if (col < n - 1) {
        w += nxt[col][i];
      }
      ret = max(ret, bt(col + 1, 1) + w);
      s -= in_col[col][i].second; //delete what previous guy covered from me.
    }
    ret = max(ret, bt(col + 1, 0));//end the sequence (don't build) but the one behind me 
  }
  return ret;
}

long long max_weights(int N, int M, vector<int> X, vector<int> Y, vector<int> W) {
  n = N;
  in_col.resize(N);
  for (int i = 0; i < M; ++i) {
    in_col[X[i]].push_back({Y[i], W[i]});
  }
  for (int i = 0; i < N; ++i) {
    sort(in_col[i].begin(), in_col[i].end());
    in_col[i].push_back({N, 0});
  }
  pre.resize(N);
  for (int col = 1; col < N; ++col) {
    pre[col].resize(in_col[col].size());
    for (int i = 0; i < (int) in_col[col].size(); ++i) {
      int ptr = 0; 
      long long sum = 0; 
      while (ptr < (int) in_col[col - 1].size() && in_col[col - 1][ptr].first < in_col[col][i].first) {
        sum += in_col[col - 1][ptr].second; 
        ptr++; 
      }
      pre[col][i] = sum; 
    }
  }
  nxt.resize(N);
  for (int col = 0; col < N - 1; ++col) {
    nxt[col].resize(in_col[col].size());
    for (int i = 0; i < (int) in_col[col].size(); ++i) {
      int ptr = 0;
      long long sum = 0;
      while (ptr < (int) in_col[col + 1].size() && in_col[col + 1][ptr].first < in_col[col][i].first) {
        sum += in_col[col + 1][ptr].second;
        ptr++;
      }
      nxt[col][i] = sum; 
    }
  }
  dp.resize(N);
  for (int i = 0; i < N; ++i) {
    dp[i].assign(2, -1);
  }
  long long ans = bt(0, 0);
  return ans; 
}

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