Maximum Size Rectangle Binary Sub Matrix 1s

13 Jun 2019

int maximalRectangle(vector<vector<char> > &matrix) {
	int res = 0;
	vector<int> height;
	for (int i = 0; i < matrix.size(); ++i) {
		height.resize(matrix[i].size());
		for (int j = 0; j < matrix[i].size(); ++j) {
			height[j] = matrix[i][j] == '0' ? 0 : (1 + height[j]);
		}
		res = max(res, largestRectangleArea(height));
	}
	return res;
}

int largestRectangleArea(vector<int> &height) {
	int res = 0;
	for (int i = 0; i < height.size(); ++i) {
		if (i + 1 < height.size() && height[i] <= height[i + 1]) {
			continue;
		}
		int minH = height[i];
		for (int j = i; j >= 0; --j) {
			minH = min(minH, height[j]);
			int area = minH * (i - j + 1);
			res = max(res, area);
		}
	}
	return res;
}