Submission #629895

#	Time	Username	Problem	Language	Result	Execution time	Memory
629895		jh05013	Catfish Farm (IOI22_fish)	C++17	81 / 100	1073 ms	138756 KiB

fish

#pragma GCC optimize("Ofast")
#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<<"]";}
 
template <typename T>
struct Compress{
	int n; vector<T> arr;
	void add(T x){arr.push_back(x); n++;}
	void init(){sort(entire(arr));}
	int lb(T x){return lower_bound(entire(arr), x) - arr.begin();}
	int ub(T x){return upper_bound(entire(arr), x) - arr.begin();}
};
 
// 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, L;
	vector<int> idxs;
	Compress<int> C;
	vector<T> val, sum, prefm, sufm;
	
	SparseArray(int N): n{N} {}
 
	map<int, T> M;
	void write(int i, T x){M[i] = x;}
	void init(){
		L = sz(M);
		if(!L) return;
		sum.resize(L), prefm.resize(L), sufm.resize(L);
		for(auto [i, x]: M) C.add(i), val.push_back(x);
		C.init();
		sum[0] = prefm[0] = val[0];
		for(int i=1; i<L; i++){
			sum[i] = sum[i-1]+val[i];
			prefm[i] = max(prefm[i-1], val[i]);
		}
		idxs = C.arr;
		sufm[L-1] = val[L-1];
		for(int i=L-2; i>=0; i--)
			sufm[i] = max(sufm[i+1], val[i]);
	}
 
	T operator[](int i){
		int idx = C.lb(i);
		if(idx == L || C.arr[idx] != i) return 0;
		return val[idx];
	}
	T prefsum(int i){
		i = C.ub(i)-1;
		return i>=0? sum[i] : (T)0;
	}
	T getsum(int l, int r){return prefsum(r) - prefsum(l);}
	T allmax(){return prefm.back();}
	T prefmax(int i){
		i = C.ub(i)-1;
		return i>=0? prefm[i] : (T)0;
	}
	T sufmax(int i){
		i = C.lb(i);
		return i<L? sufm[i] : (T)0;
	}
};
 
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);
		SparseArray<ll> incmaxer(L+1), decmaxer(L+1);
		for(int y0: grid[i-1].idxs){
			incmaxer.write(y0, dinc[y0] - grid[i-1].prefsum(y0-1));
			decmaxer.write(y0, ddec[y0] + grid[i].prefsum(y0-1));
		}
		incmaxer.init(), decmaxer.init();
		for(int y: grid[i].idxs){
			ll incy = 0, decy = 0;
			if(y == 0) incy = decy = ddec[0];
			if(y == L) incy = decy = max(ddec[0], dinc[L]);
			
			ll incmax = grid[i-1].prefsum(y-1) + incmaxer.prefmax(y-1);
			incy = max(incy, incmax);
			if(y == L) decy = max(decy, incmax);
			ll decmax = -grid[i].prefsum(y-1) + decmaxer.sufmax(y+1);
			decy = max(decy, decmax);
			ndinc.write(y, incy);
			nddec.write(y, decy);
		}
		ndinc.init(), nddec.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: 6 / 6
• Subtask 3: 9 / 9
• Subtask 4: 14 / 14
• Subtask 5: 21 / 21
• Subtask 6: 17 / 17
• Subtask 7: 14 / 14
• Subtask 8: 0 / 16