Submission #705215

#	Time	Username	Problem	Language	Result	Execution time	Memory
705215		danikoynov	Catfish Farm (IOI22_fish)	C++17	61 / 100	708 ms	331192 KiB

fish

#include "fish.h"

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

const int maxn = 1e5 + 10, smalln = 3010;

vector < pair < int, int > > col[maxn];
vector < int > state[maxn];
 unordered_set < int >  state_set[maxn];
ll dp[smalln][smalln][2];
ll val[smalln][smalln], pref[smalln][smalln];

ll get_sum(int col, int left, int right)
{
    ll sum = pref[col][right];
    if (left > 0)
        sum = sum - pref[col][left - 1];
    return sum;
}

long long max_weights(int N, int M, std::vector<int> X, std::vector<int> Y,
                      std::vector<int> W)
{
    bool all_even = true, small_x = true;
    for (int i = 0; i < M; i ++)
    {
        if (X[i] % 2 != 0)
            all_even = false;
        if (X[i] > 1)
            small_x = false;
    }

    for (int i = 0; i < M; i ++)
    {
        col[X[i]].push_back({Y[i], W[i]});
    }

    for (int i = 0; i < N; i ++)
        sort(col[i].begin(), col[i].end());

    for (int i = 0; i < M; i ++)
    {
        if (X[i] != 0)
            state_set[X[i] - 1].insert(Y[i] + 1);
        if (X[i] != N - 1)
        state_set[X[i] + 1].insert(Y[i] + 1);
    }

    for (int i = 0; i < N; i ++)
    {
        state_set[i].insert(0);
        state_set[i].insert(N);
    }
    for (int i = 0; i < N; i ++)
    {
        for (auto it : state_set[i])
            state[i].push_back(it);
        sort(state[i].begin(), state[i].end());
    }

    if (all_even)
    {
        ll sum = 0;
        for (int i = 0; i < M; i ++)
            sum = sum + W[i];
        return sum;

    }
    else if (small_x)
    {

        ll zero = 0, one = 0;
        for (int i = 0; i < M; i ++)
        {
            if (X[i] == 0)
                zero += W[i];
            else
                one += W[i];
        }
        if (N == 2)
            return max(zero, one);

        int to = 0;
        ll cur = 0, ans = 0;
        for (int i = 0; i < col[0].size(); i ++)
        {
            if (cur + one > ans)
                ans = cur + one;
            cur += col[0][i].second;
            while(to < col[1].size() && col[1][to].first <= col[0][i].first)
            {
                one -= col[1][to].second;
                to ++;
            }
        }
        if (cur + one > ans)
            ans = cur + one;
        return ans;

    }

    for (int i = 0; i < M; i ++)
        val[X[i]][Y[i]] = W[i];

    /**for (int i = 0; i < N; i ++, cout << endl)
        for (int j = 0; j < N; j ++)
        cout << val[i][j] << " ";*/
    for (int j = 0; j <= N; j ++)
        dp[1][j][0] = dp[1][j][1] = 0;

    for (int i = 0; i < N; i ++)
    {
        pref[i][0] = val[i][0];
        for (int j = 1; j <= N; j ++)
        {
            pref[i][j] = pref[i][j - 1] + val[i][j];
        }
    }
    for (int i = 1; i < N; i ++)
    {

        dp[i][0][1] = dp[i - 1][0][1];
        for (int j = 1; j <= N; j ++)
        {
            dp[i][j][1] = max(dp[i][j - 1][1] + val[i - 1][j - 1], dp[i - 1][j][1]);
        }
        dp[i][N][0] = max(dp[i - 1][N][0], dp[i - 1][N][1]);
        for (int j = N - 1; j >= 0; j --)
        {
            dp[i][j][0] = max(dp[i][j + 1][0] + val[i][j], max(dp[i - 1][j][0], dp[i - 1][j][1]));
        }

        if (i > 1)
        {

            ll best = max(dp[i - 2][0][0], dp[i - 2][0][1]);
            for (int j = 1; j <= N; j ++)
            {
                dp[i][j][1] = max(best + get_sum(i - 1, 0, j - 1), dp[i][j][1]);
                best = max(best, max(dp[i - 2][j][0], dp[i - 2][j][1]));
            }
            best = max(dp[i - 2][N][0], dp[i - 2][N][1]) + get_sum(i - 1, 0, N - 1);
            for (int j = N; j > 0; j --)
            {
                dp[i][j][1] = max(best, dp[i][j][1]);
                best = max(best, max(dp[i - 2][j][0], dp[i - 2][j][1]) + get_sum(i - 1, 0, j - 1));
            }
        }

        for (int j = 0; j <= N; j ++)
        {
            if (state_set[i].find(j) == state_set[i].end())
                dp[i][j][0] = dp[i][j][1] = 0;
            //else
              // cout << i << " " << j << " " << dp[i][j][0] << endl;
        }
    }

    /**cout << "-----------" << endl;
    for (int i = 0; i < N; i ++, cout << endl)
        for (int j = 0; j <= N; j ++)
        cout << dp[i][j][0] << " ";
    cout << "-----------" << endl;
    for (int i = 0; i < N; i ++, cout << endl)
        for (int j = 0; j <= N; j ++)
        cout << dp[i][j][1] << " ";*/
    ll ans = 0;
    for (int j = 0; j <= N; j ++)
        for (int t = 0; t < 2; t ++)
            ans = max(ans, dp[N - 1][j][t]);


    return ans;

}

Compilation message (stderr)

fish.cpp: In function 'long long int max_weights(int, int, std::vector<int>, std::vector<int>, std::vector<int>)':
fish.cpp:87:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   87 |         for (int i = 0; i < col[0].size(); i ++)
      |                         ~~^~~~~~~~~~~~~~~
fish.cpp:92:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   92 |             while(to < col[1].size() && col[1][to].first <= col[0][i].first)
      |                   ~~~^~~~~~~~~~~~~~~

• Subtask 1: 3 / 3
• Subtask 2: 6 / 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