Submission #25212

#	Time	Username	Problem	Language	Result	Execution time	Memory
25212		RezwanArefin01	Split the sequence (APIO14_sequence)	C++14	0 / 100	33 ms	84764 KiB

sequence

    //Bismillahir Rahmanir Rahim
    #include <bits/stdc++.h>
    using namespace std;
    typedef long long ll;
    const int N = 100001, K = 201; 
    ll dp[2][N], p[N];
    int par[K][N];
         
    struct CHT{
    	vector<ll> m, b, id;
    	int ptr = 0; 
    	bool bad(int l1, int l2, int l3) {
    		return (b[l3] - b[l1]) * (m[l1] - m[l2]) < (b[l2] - b[l1]) * (m[l1] - m[l3]);
    	} 
    	void clear() {
    		ptr = 0;
    		m.clear(); 
    		b.clear();
    		id.clear();
    	}
    	void add(ll _m, ll _b, ll idx) { 
    		m.push_back(_m);
    		b.push_back(_b);  
    		id.push_back(idx); 
    		int s = m.size(); 
    		while(s >= 3 && bad(s-1, s-2, s-3)) {
    			s--; 
    			m.erase(m.end()-2);
    			b.erase(b.end()-2); 
    			id.erase(id.end()-2);
    		}
    	}  
    	ll f(int i, ll x) { return m[i]*x + b[i]; }
     
    	pair<ll,ll>  query(ll x) {    
    		if(ptr >= m.size()) ptr = m.size()-1;
    		while(ptr < m.size()-1 && 
    			f(ptr+1, x) >= f(ptr, x)) ptr++; 
    		return {id[ptr], f(ptr, x)};
    	}
    }; 
     
     
    void recon(int k, int n) {
    	if(!k) return; 
    	recon(k-1, par[k][n]); 
    	cout<<par[k][n]<<" ";
    }
     
    int main(int argc, char const *argv[]) {
    #ifdef LOCAL_TESTING
    	freopen("in", "r", stdin);
    #endif
    	int n, kk; cin>>n>>kk;
    	for(int i=1; i <= n; i++) {
    		cin>>p[i];
    		p[i] += p[i-1];
    	} 
    	for(int i=0; i<=1; i++) 
    		for(int j=0; j<=n; j++) 
    			dp[i][j] = -1e18; 
    	for(int i=0; i<=n; i++) 
    		dp[0][i] = 0; 
    	CHT ds; 
     
    	for(int _k=1; _k <= kk; _k++) {
    		ds.clear();
    		ds.add(0, 0, 0);
    		int k = _k & 1;
    		for(int i=_k; i<=n; i++) {  
    			auto it = ds.query(p[i]); 
    			dp[k][i] = it.second; 
    			ds.add(p[i], dp[k ^ 1][i] - p[i] * p[i], i);
    			par[_k][i] = it.first;
    		}
    	}  
    	cout<<dp[kk & 1][n]<<endl; 	
    	recon(kk, n);
    }

Compilation message (stderr)

sequence.cpp: In member function 'std::pair<long long int, long long int> CHT::query(ll)':
sequence.cpp:36:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       if(ptr >= m.size()) ptr = m.size()-1;
              ^
sequence.cpp:37:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       while(ptr < m.size()-1 && 
                 ^

• Subtask 1: 0 / 11
• Subtask 2: 0 / 11
• Subtask 3: 0 / 11
• Subtask 4: 0 / 17
• Subtask 5: 0 / 21
• Subtask 6: 0 / 29