Submission #804537

#	Time	Username	Problem	Language	Result	Execution time	Memory
804537		phoebe	Catfish Farm (IOI22_fish)	C++17	100 / 100	139 ms	36556 KiB

fish

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

#define ll long long
#define FOR(i, n) for (int i = 0; i < n; i++)
#define PB push_back
#define pii pair<int, int>
#define F first
#define S second
#define ALL(x) x.begin(), x.end()
const int INF = 1e9 + 7;

const int maxn = 1e5 + 10;
int n, m;
vector<pii> fish[maxn]; // {y, w}
vector<ll> include[maxn], includent[maxn];

ll max_weights(int N, int M, vector<int> x, 
vector<int> y, vector<int> w){
    n = N, m = M;
    FOR(i, m) fish[x[i]].PB({y[i], w[i]});
    fish[0].PB({n, 0}); sort(ALL(fish[0]));
    include[0].assign(fish[0].size(), 0); 
    includent[0].assign(fish[0].size(), 0);
    for (int k = 1; k < n; k++){
        fish[k].PB({n, 0}); sort(ALL(fish[k]));
        // case 0: k + 1 pier is >= k pier
        // k + 1 pier determines fish on k
        // k - 1 pier length does not matter
        ll best = 0;
        for (auto v : include[k - 1]) best = max(best, v);
        include[k].assign(fish[k].size(), best);
        includent[k].assign(fish[k].size(), best);
        // case 1: k pier is >= k - 1 pier
        // k pier determines which fish can be caught on k - 1
        ll j = 0, sum = 0, mx = -INF;
        FOR(i, fish[k].size()){ 
            // building a pier of length y[fish[k][i]] - 1
            while (j < fish[k - 1].size() && fish[k - 1][j].F < fish[k][i].F){
                mx = max(mx, includent[k - 1][j] - sum);
                sum += fish[k - 1][j].S; j++;
            }
            include[k][i] = max(include[k][i], mx + sum);
            includent[k][i] = max(includent[k][i], mx + sum);
        }
        // case 2: k pier is <= k - 1 pier
        // k - 1 pier determines which fish can be caught on k
        j = fish[k - 1].size(), sum = 0, mx = -INF;
        for (int i = fish[k].size() - 1; i >= 0; i--){
            // building a pier of length y[fish[k][i]] - 1
            while (j > 0 && fish[k - 1][j - 1].F > fish[k][i].F){
                j--;
                mx = max(mx, include[k - 1][j] - sum);
            }
            sum += fish[k][i].S;
            include[k][i] = max(include[k][i], mx + sum);
        }
        // cout << "we are on x = " << k << endl;
        // for (auto v : include[k]) cout << v << ' '; cout << endl;
        // for (auto v : includent[k]) cout << v << ' '; cout << endl;
        // cout << endl;
    }
    ll re = 0;
    for (auto v : include[n - 1]) re = max(re, v);
    return re;
}

// signed main(){
//     cout << max_weights(5, 4, {0, 1, 4, 3}, 
//     {2, 1, 4, 3}, {5, 2, 1, 3});
// }

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:5:37: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    5 | #define FOR(i, n) for (int i = 0; i < n; i++)
......
   37 |         FOR(i, fish[k].size()){
      |             ~~~~~~~~~~~~~~~~~        
fish.cpp:37:9: note: in expansion of macro 'FOR'
   37 |         FOR(i, fish[k].size()){
      |         ^~~
fish.cpp:39:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |             while (j < fish[k - 1].size() && fish[k - 1][j].F < fish[k][i].F){
      |                    ~~^~~~~~~~~~~~~~~~~~~~

• 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