From a415a953c3f1bb741f14a4ba06f067e6d94653ed Mon Sep 17 00:00:00 2001
From: Ankana Pari <143877643+ankana2113@users.noreply.github.com>
Date: Sun, 9 Mar 2025 03:05:07 +0530
Subject: [PATCH] Add largest rectangle histogram (#12269)

* added ridge regression

* added ridge regression

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* added ridge regression

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* ridge regression

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* resolved errors

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* resolved conflicts

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* added doctests

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* ruff and minor checks

* minor chenges

* minor checks

* minor checks

* minor changes

* descriptive names

* Fix ruff check in loss_functions.py

* fixed pre-commit issues

* added largest rectangle histogram function

* added largest rectangle histogram function

* Update frequent_pattern_growth.py

* Update loss_functions.py

* Delete machine_learning/ridge_regression/__init__.py

* Delete machine_learning/ridge_regression/ADRvsRating.csv

* Delete machine_learning/ridge_regression/ridge_regression.py

* Delete machine_learning/ridge_regression/test_ridge_regression.py

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Maxim Smolskiy <mithridatus@mail.ru>
---
 .../stacks/largest_rectangle_histogram.py     | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 data_structures/stacks/largest_rectangle_histogram.py

diff --git a/data_structures/stacks/largest_rectangle_histogram.py b/data_structures/stacks/largest_rectangle_histogram.py
new file mode 100644
index 000000000..7575bd9f6
--- /dev/null
+++ b/data_structures/stacks/largest_rectangle_histogram.py
@@ -0,0 +1,39 @@
+def largest_rectangle_area(heights: list[int]) -> int:
+    """
+    Inputs an array of integers representing the heights of bars,
+    and returns the area of the largest rectangle that can be formed
+
+    >>> largest_rectangle_area([2, 1, 5, 6, 2, 3])
+    10
+
+    >>> largest_rectangle_area([2, 4])
+    4
+
+    >>> largest_rectangle_area([6, 2, 5, 4, 5, 1, 6])
+    12
+
+    >>> largest_rectangle_area([1])
+    1
+    """
+    stack: list[int] = []
+    max_area = 0
+    heights = [*heights, 0]  # make a new list by appending the sentinel 0
+    n = len(heights)
+
+    for i in range(n):
+        # make sure the stack remains in increasing order
+        while stack and heights[i] < heights[stack[-1]]:
+            h = heights[stack.pop()]  # height of the bar
+            # if stack is empty, it means entire width can be taken from index 0 to i-1
+            w = i if not stack else i - stack[-1] - 1  # calculate width
+            max_area = max(max_area, h * w)
+
+        stack.append(i)
+
+    return max_area
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()