Submission #769549

#	Time	Username	Problem	Language	Result	Execution time	Memory
769549		mousebeaver	Catfish Farm (IOI22_fish)	C++17	18 / 100	69 ms	29920 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--;
                }
                if(grid[i-1][index].height == grid[i][j].height)
                {
                    grid[i][j].bigPier = max(grid[i-1][index].bigPier, max(grid[i-1][index].noPier, grid[i-1][index].smallPier));
                    index--;
                }
                while(index >= 0)
                {
                    sum += grid[i-1][index].weight;
                    grid[i][j].bigPier = max(grid[i][j].bigPier, max(grid[i-1][index].bigPier, grid[i-1][index].noPier)+sum);
                    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 = grid[i][j].weight;
                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