Submission #222967

#	Time	Username	Problem	Language	Result	Execution time	Memory
222967		abeker	Rectangles (IOI19_rect)	C++17	72 / 100	2179 ms	1048580 KiB

rect

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

typedef long long ll;
typedef pair <int, int> pii;

const int MAXN = 2.5e3 + 5;

class Fenwick {
	int n;
	int f[MAXN];
	public:
		Fenwick(int _n) {
			n = _n;
			for (int i = 0; i <= n; i++)
				f[i] = 0;
		}
		Fenwick(){}
		void update(int x, int val) {
			for (x++; x <= n; x += x & -x)
				f[x] += val;
		}
		int get(int x) {
			int res = 0;
			for (x++; x; x -= x & -x)
				res += f[x];
			return res;
		}
		int query(int l, int r) {
			return get(r) - get(l - 1);
		}
};

int foo[MAXN];
vector <int> rows[MAXN][MAXN], cols[MAXN][MAXN];
vector <pii> in[MAXN][MAXN], out[MAXN][MAXN];

void find_pairs(const vector <int> &arr, vector <int> ref[MAXN][MAXN], int idx) {
	int n = arr.size(), sz = 0;
	for (int i = 0; i < n; i++) {
		while (sz && arr[foo[sz - 1]] < arr[i])
			sz--;
		if (sz && foo[sz - 1] < i - 1)
			ref[foo[sz - 1]][i].push_back(idx);
		foo[sz++] = i;
	}
	sz = 0;
	for (int i = n - 1; i >= 0; i--) {
		while (sz && arr[foo[sz - 1]] < arr[i])
			sz--;
		if (sz && arr[foo[sz - 1]] > arr[i] && foo[sz - 1] > i + 1)
			ref[i][foo[sz - 1]].push_back(idx);
		foo[sz++] = i;
	}
}

vector <pii> get_blocks(const vector <int> &v, int bound) {
	vector <pii> res;
	int sz = v.size(), lst = 0;
	for (int i = 0; i < sz; i++) 
		if (i == sz - 1 || v[i + 1] > v[i] + 1) {
			res.push_back({max(v[lst] - 1, 0), min(v[i] + 1, bound - 1)});
			lst = i + 1;
		}
	return res;
}

ll count_rectangles(vector <vector <int>> a) {
	int N = a.size();
	int M = a[0].size();
	
	for (int i = 0; i < N; i++) 
		find_pairs(a[i], rows, i);
	
	for (int j = 0; j < M; j++) {
		vector <int> curr;
		for (int i = 0; i < N; i++)
			curr.push_back(a[i][j]);
		find_pairs(curr, cols, j);
	}
	
	for (int i = 0; i < N; i++)
		for (int j = 0; j < N; j++) {
			vector <pii> tmp = get_blocks(cols[i][j], M);
			for (auto it : tmp) 
				for (int k = it.first; k <= it.second; k++) {
					in[k][it.first].push_back({i, j});
					out[k][it.second].push_back({i, j});
				}
		}
	
	ll sol = 0;
	vector <Fenwick> loga(N);
	for (int i = 0; i < N; i++)
		loga[i] = Fenwick(N);
	for (int i = 0; i < M; i++)
		for (int j = 0; j < M; j++) {
			for (auto it : in[i][j])
				loga[it.first].update(it.second, 1);
			vector <pii> tmp = get_blocks(rows[i][j], N);
			for (auto it : tmp)
				for (int k = it.first; k <= it.second; k++)
					sol += loga[k].query(it.first, it.second);
			for (auto it : out[i][j])
				loga[it.first].update(it.second, -1);
		}
	
	return sol;
}

• Subtask 1: 8 / 8
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 22 / 22
• Subtask 5: 10 / 10
• Subtask 6: 13 / 13
• Subtask 7: 0 / 28