From 8c853f75d200c7012d21f161398fcafc78872758 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=9C=D0=BE=D1=80=D0=B5=D0=B2=20=D0=90=D0=BB=D0=B5=D0=BA?=
 =?UTF-8?q?=D1=81=D0=B0=D0=BD=D0=B4=D1=80?= <hikjik@yandex.ru>
Date: Mon, 16 Oct 2023 12:03:19 +0300
Subject: [PATCH] Maximal Rectangle

---
 CMakeLists.txt                             |  1 +
 solutions/maximal-rectangle/CMakeLists.txt |  1 +
 solutions/maximal-rectangle/solution.hpp   | 38 ++++++++++++++++++++++
 solutions/maximal-rectangle/test.cpp       | 33 +++++++++++++++++++
 4 files changed, 73 insertions(+)
 create mode 100644 solutions/maximal-rectangle/CMakeLists.txt
 create mode 100644 solutions/maximal-rectangle/solution.hpp
 create mode 100644 solutions/maximal-rectangle/test.cpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 04d43e56..a4c3526d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -333,6 +333,7 @@ add_task(max-number-of-k-sum-pairs)
 add_task(max-pair-sum-in-an-array)
 add_task(max-points-on-a-line)
 add_task(maximal-network-rank)
+add_task(maximal-rectangle)
 add_task(maximal-square)
 add_task(maximize-score-after-n-operations)
 add_task(maximize-the-confusion-of-an-exam)
diff --git a/solutions/maximal-rectangle/CMakeLists.txt b/solutions/maximal-rectangle/CMakeLists.txt
new file mode 100644
index 00000000..51d99e64
--- /dev/null
+++ b/solutions/maximal-rectangle/CMakeLists.txt
@@ -0,0 +1 @@
+add_catch(test_maximal_rectangle test.cpp)
diff --git a/solutions/maximal-rectangle/solution.hpp b/solutions/maximal-rectangle/solution.hpp
new file mode 100644
index 00000000..8cdc7208
--- /dev/null
+++ b/solutions/maximal-rectangle/solution.hpp
@@ -0,0 +1,38 @@
+#pragma once
+
+#include <stack>
+#include <vector>
+
+class Solution {
+public:
+  static int maximalRectangle(const std::vector<std::vector<char>> &matrix) {
+    const int n = matrix.size(), m = matrix.back().size();
+
+    int max_rectangle = 0;
+    std::vector<int> heights(m);
+    for (int i = 0; i < n; ++i) {
+      for (int j = 0; j < m; ++j) {
+        heights[j] = matrix[i][j] == '0' ? 0 : heights[j] + 1;
+      }
+      max_rectangle = std::max(max_rectangle, largestRectangleArea(heights));
+    }
+    return max_rectangle;
+  }
+
+private:
+  static int largestRectangleArea(const std::vector<int> &heights) {
+    const int n = heights.size();
+    std::stack<int> stack;
+    int max_area = 0;
+    for (int i = 0; i <= n; ++i) {
+      while (!stack.empty() && (i == n || heights[stack.top()] > heights[i])) {
+        const auto height = heights[stack.top()];
+        stack.pop();
+        const auto width = stack.empty() ? i : i - stack.top() - 1;
+        max_area = std::max(max_area, height * width);
+      }
+      stack.push(i);
+    }
+    return max_area;
+  }
+};
diff --git a/solutions/maximal-rectangle/test.cpp b/solutions/maximal-rectangle/test.cpp
new file mode 100644
index 00000000..c3b0e69c
--- /dev/null
+++ b/solutions/maximal-rectangle/test.cpp
@@ -0,0 +1,33 @@
+#include <catch.hpp>
+
+#include <solution.hpp>
+
+TEST_CASE("Simple") {
+  struct TestCase {
+    std::vector<std::vector<char>> matrix;
+    int expected;
+  };
+
+  std::vector<TestCase> test_cases{
+      {
+          .matrix{{'1', '0', '1', '0', '0'},
+                  {'1', '0', '1', '1', '1'},
+                  {'1', '1', '1', '1', '1'},
+                  {'1', '0', '0', '1', '0'}},
+          .expected = 6,
+      },
+      {
+          .matrix{{'0'}},
+          .expected = 0,
+      },
+      {
+          .matrix{{'1'}},
+          .expected = 1,
+      },
+  };
+
+  for (const auto &[matrix, expected] : test_cases) {
+    const auto actual = Solution::maximalRectangle(matrix);
+    REQUIRE(expected == actual);
+  }
+}