Submission #769524

#	Time	Username	Problem	Language	Result	Execution time	Memory
769524		mousebeaver	Catfish Farm (IOI22_fish)	C++17	18 / 100	72 ms	31264 KiB

fish

#define ll long long
#define pll pair<ll, ll>
#include "fish.h"
#include <bits/stdc++.h>
using namespace std;

struct fish
{
    ll height;
    ll weight;
    ll below;
    ll above; //Sums of weights in column
    ll bigPier; //No bigger pier in the previous column -> first one to be caught
    ll noPier; //No pier in this column -> first one to be caught
    ll smallPier; //Bigger pier in the previous column -> first one not below a pier
};

bool operator < (fish a, fish b)
{
    return (a.height < b.height);
}

long long max_weights(int N, int M, std::vector<int> X, std::vector<int> Y, std::vector<int> W) 
{
    bool sub1 = true;
    bool sub2 = true;
    bool sub3 = true;

    for(ll i = 0; i < M; i++)
    {
        if(X[i] % 2 == 1)
        {
            sub1 = false;
        }
        if(X[i] > 1)
        {
            sub2 = false;
        }
        if(Y[i] != 0)
        {
            sub3 = false;
        }
    }

    if(sub1)
    {
        ll sum = 0;
        for(int i : W)
        {
            sum += (ll) i;
        }
        return sum;
    }

    if(sub2)
    {
        vector<pll> left(0);
        vector<pll> right(0); //Height, weight
        ll lsum = 0;
        ll rsum = 0;

        for(ll i = 0; i < M; i++)
        {
            if(X[i] == 0)
            {
                left.push_back({Y[i], W[i]});
                lsum += W[i];
            }
            else
            {
                right.push_back({Y[i], W[i]});
                rsum += W[i];
            }
        }
        sort(left.begin(), left.end());
        sort(right.begin(), right.end());

        ll output = max(lsum, rsum);

        if(N > 2)
        {
            ll lindex = -1;
            ll rindex = -1;
            ll shadow = 0;
            ll roof = 0;
            for(ll i = 0; i < N; i++)
            {
                while(lindex+1 < (ll) left.size() && left[lindex+1].first <= i)
                {
                    lindex++;
                    shadow += left[lindex].second;
                }
                while(rindex+1 < (ll) right.size() && right[rindex+1].first <= i)
                {
                    rindex++;
                    roof += right[rindex].second;
                }
                output = max(output, shadow + rsum - roof);
            }
        }

        return output;
    }
    
    if(sub3)
    {
        vector<ll> w(N, 0);
        for(ll i = 0; i < M; i++)
        {
            w[X[i]] = W[i];
        }

        vector<vector<ll>> dp(N, vector<ll> (3, 0)); //Pier, no pier + uncaught, no pier + caught
        for(ll i = 1; i < N; i++)
        {
            //Pier:
            dp[i][0] = dp[i-1][0];
            dp[i][0] = max(dp[i][0], dp[i-1][1]+w[i-1]);
            dp[i][0] = max(dp[i][0], dp[i-1][2]);

            //no pier + uncaught:
            dp[i][1] = dp[i-1][1];
            dp[i][1] = max(dp[i][1], dp[i-1][2]);

            //no pier + caught:
            dp[i][2] = dp[i-1][0]+w[i];
        }

        return max(max(dp[N-1][0], dp[N-1][1]), dp[N-1][2]);
    }

    vector<vector<fish>> grid(N, vector<fish> (0));
    for(ll i = 0; i < M; i++)
    {
        fish f;
        f.height = Y[i];
        f.weight = W[i];
        grid[X[i]].push_back(f);
    }

    fish top, bottom;
    top.height = N;
    top.weight = 0;
    bottom.height = -1;
    bottom.weight = 0;
    for(ll i = 0; i < N; i++)
    {
        grid[i].push_back(top);
        grid[i].push_back(bottom);
        sort(grid[i].begin(), grid[i].end());
        ll sum = 0;
        for(ll j = 0; j < (ll) grid[i].size(); j++)
        {
            grid[i][j].below = sum;
            sum += grid[i][j].weight;
        }
        sum = 0;
        for(ll j = grid[i].size()-1; j >= 0; j--)
        {
            grid[i][j].above = sum;
            sum += grid[i][j].weight;
        }
    }

    for(ll i = 0; i < (ll) grid[0].size(); i++)
    {
        grid[0][i].bigPier = 0;
        grid[0][i].smallPier = 0;
        grid[0][i].noPier = 0;
    }

    for(ll i = 1; i < N; i++)
    {
        //calculate DP[i][j]:
        for(ll j = 0; j < (ll) grid[i].size(); j++)
        {
            //bigPier
            grid[i][j].bigPier = 0;
            ll sum = 0;
            ll index = grid[i-1].size()-1; //Index of first lower fish in previous column
            while(index >= 0 && grid[i-1][index].height > grid[i][j].height)
            {
                index--;
            }
            while(index >= 0)
            {
                grid[i][j].bigPier = max(grid[i][j].bigPier, max(grid[i-1][index].bigPier, grid[i-1][index].noPier)+sum);
                sum += grid[i-1][index].weight;
                index--;
            }

            //noPier
            grid[i][j].noPier = 0;
            for(ll k = 0; k < (ll) grid[i-1].size(); k++)
            {
                grid[i][j].noPier = max(max(grid[i-1][k].bigPier, grid[i-1][k].smallPier), grid[i-1][k].noPier);
            }
            sum = 0;
            index = 0;
            for(ll k = 0; k < (ll) grid[i-1].size() && grid[i-1][k].height <= grid[i][j].height; k++)
            {
                while(grid[i][index].height < grid[i-1][k].height)
                {
                    sum += grid[i][index].weight;
                    index++;
                }
                grid[i][j].noPier = max(grid[i][j].noPier, max(grid[i-1][k].smallPier, grid[i-1][k].bigPier)+sum);
            }
            
            //smallPier
            grid[i][j].smallPier = 0;
            sum = 0;
            index = 0;
            ll shadowIndex = j;
            while(index < (ll) grid[i-1].size() && grid[i-1][index].height <= grid[i][j].height)
            {
                index++;
            }
            while(index < (ll) grid[i-1].size())
            {
                while(shadowIndex+1 < (ll) grid[i].size() && grid[i][shadowIndex+1].height <= grid[i-1][index].height)
                {
                    shadowIndex++;
                    sum += grid[i][shadowIndex].weight;
                }
                grid[i][j].smallPier = max(grid[i][j].smallPier, max(grid[i-1][index].bigPier, grid[i-1][index].smallPier)+sum);
                index++;
            }
        }
    }

    ll output = 0;
    for(fish f : grid[N-1])
    {
        ll val = max(max(f.noPier, f.bigPier), f.smallPier);
        output = max(output, val);
    }
    
    return output;
}

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