Submission #629568

#	Time	Username	Problem	Language	Result	Execution time	Memory
629568		jh05013	Catfish Farm (IOI22_fish)	C++17	35 / 100	1085 ms	2097152 KiB

fish

#include <bits/stdc++.h>
using namespace std;
void OJize(){cin.tie(NULL);ios_base::sync_with_stdio(false);}

typedef long long ll;
const int IINF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3f;
#define sz(X) (int)((X).size())
#define entire(X) X.begin(),X.end()
template <class T1, class T2>ostream&operator<<(ostream &os,pair<T1,T2>const&x){os<<'('<<x.first<<", "<<x.second<<')';return os;}
template <class Ch, class Tr, class Container>basic_ostream<Ch,Tr>&operator<<(basic_ostream<Ch,Tr>&os,Container const&x){os<<"[ ";for(auto&y:x)os<<y<<" ";return os<<"]";}

// NOTE: this is not a "sparse table" related to
// binary lifting, it's literally an array which is sparse!!
template<typename T>
struct SparseArray{
	// not actually sparse yet!!
	int n;
	vector<T> arr, sum;
	vector<bool> written;
	vector<int> nonempty;
	SparseArray(int N): n{N}, arr(N), sum(N), written(N){}

	void write(int i, T x){arr[i] = x; written[i] = true;}
	void init(){
		sum[0] = arr[0];
		for(int i=1; i<n; i++) sum[i] = sum[i-1]+arr[i];
		for(int i=0; i<n; i++) if(written[i])
			nonempty.push_back(i);
	}

	T operator[](int i){return arr[i];}
	T prefsum(int i){return i>=0? sum[i] : (T)0;}
	T getsum(int l, int r){return prefsum(r) - prefsum(l);}
	T allmax(){
		return *max_element(entire(arr));
	}
};

ll max_weights(int L, int n,
vector<int> X, vector<int> Y, vector<int> W){
	vector<SparseArray<ll>> grid(L, SparseArray<ll>(L+1));
	for(int i=0; i<L; i++)
		grid[i].write(0, 0), grid[i].write(L, 0);
	for(int i=0; i<n; i++) grid[X[i]].write(Y[i], (ll)W[i]);
	for(auto &A: grid) A.init();

	SparseArray<ll> dinc(L+1), ddec(L+1);
	dinc.init(); ddec.init();
	// column _,
	// last column height j,
	// next will increase/decrease
	for(int i=1; i<L; i++){
		SparseArray<ll> ndinc(L+1), nddec(L+1);
		for(int y: grid[i].nonempty){
			ll incy = 0, decy = 0;
			if(y == 0) incy = decy = ddec[0];
			if(y == L) incy = decy = max(ddec[0], dinc[L]);
			ll inc_base = grid[i-1].prefsum(y-1);
			for(int y0: grid[i-1].nonempty) if(y0 < y){ // inc
				// take [i-1][y0 to y-1]
				ll val = inc_base + dinc[y0] - grid[i-1].prefsum(y0-1);
				incy = max(incy, val);
				if(y == L) decy = max(decy, val);
			}
			ll dec_base = -grid[i].prefsum(y-1);
			for(int y0: grid[i-1].nonempty) if(y0 > y){ // dec
				// take [i][y to y0-1]
				ll val = dec_base + ddec[y0] + grid[i].prefsum(y0-1);
				decy = max(decy, val);
			}
			ndinc.write(y, incy);
			nddec.write(y, decy);
		}
		ndinc.init(); ddec.init();
		dinc = ndinc, ddec = nddec;
	}

	return max(dinc.allmax(), ddec.allmax());
}

#ifdef jh
int main(){OJize();
	int n; cin>>n;
	vector<int> X, Y, W;
	for(int i=0; i<n; i++) for(int j=0; j<n; j++){
		int x; cin>>x;
		if(x){
			X.push_back(j);
			Y.push_back(n-1-i);
			W.push_back(x);
		}
	}
	cout << max_weights(n, sz(X), X, Y, W);
}
#endif

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