Submission #630195

#	Time	Username	Problem	Language	Result	Execution time	Memory
630195		ffao	Catfish Farm (IOI22_fish)	C++17	100 / 100	520 ms	81676 KiB

fish

#include "fish.h"

using namespace std;
#include <vector>
#include <algorithm>

long long max_weights(int N, int M, std::vector<int> X, std::vector<int> Y, std::vector<int> W) {
    vector< vector<int> > Ys_per_col(N);
    
    vector<long long> colsum(N);
    for (int i = 0; i < M; i++) colsum[X[i]] += W[i];
    
    auto find = [&](int x, int y){ return (upper_bound(Ys_per_col[x].begin(), Ys_per_col[x].end(), y) - Ys_per_col[x].begin()) - 1; };
    
    for (int i = 0; i < M; i++) { X.push_back(X[i]); Y.push_back(Y[i]+1); W.push_back(0); }
    for (int i = 0; i < N; i++) { X.push_back(i); Y.push_back(-1); W.push_back(0); }
    for (int i = 0; i < N; i++) { X.push_back(i); Y.push_back(N); W.push_back(0); }
    for (int i = 0; i < X.size(); i++) {
        Ys_per_col[X[i]].push_back(Y[i]);
        if (X[i] > 0) Ys_per_col[X[i]-1].push_back(Y[i]);
        if (X[i]+1 < N) Ys_per_col[X[i]+1].push_back(Y[i]);
    }
    
    for (int i = 0; i < N; i++) {
        sort(Ys_per_col[i].begin(), Ys_per_col[i].end());
        Ys_per_col[i].erase( unique(Ys_per_col[i].begin(), Ys_per_col[i].end()), Ys_per_col[i].end());
    }
    
    vector< vector<int> > WW(N);
    for (int i = 0; i < N; i++) WW[i].resize(Ys_per_col[i].size());
    for (int i = 0; i < M; i++) {
        int idx = find(X[i], Y[i]);
        WW[X[i]][idx] = max(WW[X[i]][idx], W[i]);
    }
    
    vector< vector<long long> > dp[2];
    for (int i = 0; i < 2; i++) {
        dp[i].resize(N);
        for (int j = 0; j < N; j++) dp[i][j].resize(Ys_per_col[j].size());
    }
    
    long long ans = 0;    
    for (int i = 1; i < N; i++) {
        if (i >= 2) dp[0][i][0] = dp[1][i-2][0];
        if (i >= 2) dp[0][i][ Ys_per_col[i].size() - 1 ] = dp[0][i-2][ Ys_per_col[i-2].size() - 1 ] + colsum[i-1];
        
        for (int j = 1; j < (int)Ys_per_col[i].size(); j++) {
            dp[0][i][j] = max(dp[0][i][j], dp[0][i][j-1] + WW[i-1][ find(i-1, Ys_per_col[i][j-1]) ]);
            dp[0][i][j] = max(dp[0][i][j], dp[0][i-1][ find(i-1, Ys_per_col[i][j]) ]);
        }
        
        dp[1][i][ Ys_per_col[i].size() - 1 ] = dp[0][i-1][ Ys_per_col[i-1].size() - 1 ];
        for (int j = (int)Ys_per_col[i].size() - 2; j >= 0; j--) {
            dp[1][i][j] = dp[1][i][j+1] + WW[i][j]; 
            dp[1][i][j] = max( dp[1][i][j], dp[1][i-1][ find(i-1, Ys_per_col[i][j] - 1) + 1 ]);
        }
        
        for (int j = 0; j < (int)Ys_per_col[i].size(); j++) {
            ans = max(ans, dp[0][i][j]);
            ans = max(ans, dp[1][i][j]);
        }
    }
    
    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:18:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |     for (int i = 0; i < X.size(); i++) {
      |                     ~~^~~~~~~~~~

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