Submission #628221

#	Time	Username	Problem	Language	Result	Execution time	Memory
628221		MarkBcc168	Catfish Farm (IOI22_fish)	C++17	100 / 100	146 ms	20836 KiB

fish

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

long long max_weights(int n, int m, std::vector<int> x, std::vector<int> y, std::vector<int> w){
    vector<ll> col[n];
    for(int i=0; i<m; ++i){
        col[x[i]].push_back(i);
    }
    for(int i=0; i<n; ++i){
        sort(col[i].begin(), col[i].end(),
            [&](int p, int q){return y[p] < y[q];});
    }
    vector<ll> up(m,0), down(m,0);
    vector<ll> up_max(n,0), down_max(n,0);
    for(int i=0; i<n; ++i){
        if(col[i].size() == 0){
            if(i==0){
                up_max[i] = 0;
                down_max[i] = 0;
            }
            else{
                up_max[i] = up_max[i-1];
                down_max[i] = down_max[i-1];
            }
            continue;
        }
            
        //case 1: delete (i-1)-st column and start over
        ll mx = (i<2) ? 0LL : max(up_max[i-2], down_max[i-1]);
        for(int j=0; j<col[i].size(); ++j){
            if(j==0) up[col[i][0]] = mx + w[col[i][0]];
            else{
                up[col[i][j]] = up[col[i][j-1]] + w[col[i][j]];
            }
        }
        if(i > 0){
            mx = (i<2) ? 0LL : max(up_max[i-2], down_max[i-2]);
            for(int j=col[i].size()-1; j>=0; --j){
                if(j==col[i].size()-1) down[col[i][j]] = mx + w[col[i][j]];
                else{
                    down[col[i][j]] = down[col[i][j+1]] + w[col[i][j]];
                }
            }
        }
        
        //case 2: actually using the previous column
        if(i>0 && col[i-1].size() > 0){
            int p, x = col[i-1].size();
            p = -1; 
            for(int j=0; j<col[i].size(); j++){
                while(p < x-1 && y[col[i-1][p+1]] < y[col[i][j]]) p++;
                if(p==-1) continue;
                if(j==0) up[col[i][j]] = max(up[col[i][j]], up[col[i-1][p]] + w[col[i][j]]);
                else{
                    up[col[i][j]] = max({up[col[i][j]],
                        up[col[i-1][p]] + w[col[i][j]],
                        up[col[i][j-1]] + w[col[i][j]]});
                }
            }
            p = x;
            if(i>1){
                for(int j=col[i].size()-1; j>=0; j--){
                    while(p > 0 && y[col[i-1][p-1]] > y[col[i][j]]) p--;
                    if(p==x) continue;
                    if(j==col[i].size()-1) down[col[i][j]] = max(down[col[i][j]], down[col[i-1][p]] + w[col[i][j]]);
                    else{
                        down[col[i][j]] = max(down[col[i][j]],
                            max(down[col[i-1][p]],down[col[i][j+1]]) + w[col[i][j]]);
                    }
                }
            }
        }
        if(i==0){
            up_max[i] = up[col[i][col[i].size()-1]];
            down_max[i] = down[col[i][0]];
        }
        else{
            up_max[i] = max(up_max[i-1], up[col[i][col[i].size()-1]]);
            down_max[i] = max(down_max[i-1], down[col[i][0]]);
        }
    }
    return max(up_max[n-2], down_max[n-1]);
}

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:31:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |         for(int j=0; j<col[i].size(); ++j){
      |                      ~^~~~~~~~~~~~~~
fish.cpp:40:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |                 if(j==col[i].size()-1) down[col[i][j]] = mx + w[col[i][j]];
      |                    ~^~~~~~~~~~~~~~~~~
fish.cpp:51:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   51 |             for(int j=0; j<col[i].size(); j++){
      |                          ~^~~~~~~~~~~~~~
fish.cpp:66:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |                     if(j==col[i].size()-1) down[col[i][j]] = max(down[col[i][j]], down[col[i-1][p]] + w[col[i][j]]);
      |                        ~^~~~~~~~~~~~~~~~~

• 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