Submission #696563

#	Time	Username	Problem	Language	Result	Execution time	Memory
696563		BobCompetitiveProgramming	Catfish Farm (IOI22_fish)	C++17	0 / 100	145 ms	36764 KiB

fish

#include <bits/stdc++.h>
using namespace std; using ll=int;
#define all(x) begin(x), end(x)

 
ll max_weights(int N, int M, vector<int> X, vector<int> Y, vector<int> W){
    map<array<ll,2>, ll> fish; // Row sorted
    for(ll i=0; i<M; ++i) fish[{Y[i], X[i]}] = W[i];

    vector<map<ll,ll>> prefix(N);
    for(auto& f : fish){
        ll y=f.first[0], x=f.first[1], w=f.second;
        auto it = prefix[x].end();
    
        if(!prefix[x].size())
            prefix[x][y]=w; 
        else 
            prefix[x][y]=w+prev(prefix[x].end())->first; 
            
    }
    
    

    map<array<ll, 2>, ll> dp, prev;
    prev[{0, 1}]=0; // Prev height and state [1: increasing, -1: decreasing, -5/-6: peak] = ans.
    // -5 previously increased, -6 previously decreased.
    set<array<ll,2>> vis;

    ll ret=0; 
    
    for(ll i=0; i<N; ++i){
        //cout << endl << endl;
        if(!prefix[i].size()) continue;
        for(auto& e : prev){
            
            if(vis.count(e.first)) continue;
            vis.insert(e.first);
            // cout <<e.first[0] << " state : "<< e.first[1] << " ans : " << e.second <<  endl;
            ll prevHeight=e.first[0], state=e.first[1], curr_ans=e.second;
            ll taken=0;
            ret=max(ret, curr_ans); 
            if(i && prefix[i-1].size()){
                
                auto iter=(prefix[i-1].upper_bound(prevHeight))--;
                ll taken=iter->second;
            } 
            if(state==1){
                dp[{0, 1}]=curr_ans;
                dp[{N-1, -1}]=curr_ans+((prefix[i].upper_bound(N-1))--)->second - taken;
                auto it=prefix[i].lower_bound(prevHeight);
                while(it != prefix[i].end()){
                    ll currHeight=it->first; 
                    currHeight-=1; 
                    if(currHeight==prevHeight) dp[{currHeight, -5}]=curr_ans;
                    else {
                        ll new_ans=curr_ans+((prefix[i].upper_bound(currHeight))--)->second - taken;
                        dp[{currHeight, 1}]=new_ans;
                        dp[{currHeight, -1}]=new_ans; 
                    }
                    ++it;
                } 
            } else if(state==-1){
                dp[{0, 1}]=curr_ans;
                auto it=prefix[i].lower_bound(prevHeight);
                while(it != prefix[i].begin()){
                    ll currHeight=it->first;
                    if(currHeight==prevHeight) dp[{currHeight, -6}]=curr_ans;
                    else {
                        ll new_ans=curr_ans+max((ll)0,((prefix[i].upper_bound(currHeight))--)->second - taken);
                        dp[{currHeight, 1}]=new_ans;
                        dp[{currHeight, -1}]=new_ans;
                    }
                    --it;
                }

            } else { // state:saddle;
                if(state==-5){ // was increasing
                    state=-1;
                    dp[{0, 1}]=curr_ans;
                    auto it=prefix[i].lower_bound(prevHeight);
                    while(it != prefix[i].begin()){
                        ll currHeight=it->first;
                        if(currHeight!=prevHeight) {
                            dp[{currHeight, state}]=curr_ans;
                        }
                        --it;
                    }
                } else if(state==-6){ // was decreasing
                    state=1;
                    
                    dp[{N-1, -1}]=curr_ans+((prefix[i].upper_bound(N-1))--)->second - taken;;
                    auto it=prefix[i].lower_bound(prevHeight);
                    
                    while(it != prefix[i].end()){
                        ll currHeight=it->first;
                        if(currHeight!=prevHeight) {
                            dp[{currHeight, state}]=curr_ans+((prefix[i].upper_bound(currHeight))--)->second - taken;
                        }
                        ++it;
                    } 
                }
            }
        }
        prev=dp;
        dp.clear();
        vis.clear();
    }
    return ret;
}

Compilation message (stderr)

fish.cpp: In function 'll max_weights(int, int, std::vector<int>, std::vector<int>, std::vector<int>)':
fish.cpp:13:14: warning: variable 'it' set but not used [-Wunused-but-set-variable]
   13 |         auto it = prefix[x].end();
      |              ^~
fish.cpp:45:20: warning: unused variable 'taken' [-Wunused-variable]
   45 |                 ll taken=iter->second;
      |                    ^~~~~

• Subtask 1: 0 / 3
• Subtask 2: 0 / 6
• Subtask 3: 0 / 9
• Subtask 4: 0 / 14
• Subtask 5: 0 / 21
• Subtask 6: 0 / 17
• Subtask 7: 0 / 14
• Subtask 8: 0 / 16