Add solution #85

Author: JoshCrozier

README.md

@@ -83,6 +83,7 @@
 81|[Search in Rotated Sorted Array II](./0081-search-in-rotated-sorted-array-ii.js)|Medium|
 82|[Remove Duplicates from Sorted List II](./0082-remove-duplicates-from-sorted-list-ii.js)|Medium|
 83|[Remove Duplicates from Sorted List](./0083-remove-duplicates-from-sorted-list.js)|Easy|
+85|[Maximal Rectangle](./0085-maximal-rectangle.js)|Hard|
 86|[Partition List](./0086-partition-list.js)|Medium|
 88|[Merge Sorted Array](./0088-merge-sorted-array.js)|Easy|
 89|[Gray Code](./0089-gray-code.js)|Medium|

solutions/0085-maximal-rectangle.js

@@ -0,0 +1,38 @@
+/**
+ * 85. Maximal Rectangle
+ * https://leetcode.com/problems/maximal-rectangle/
+ * Difficulty: Hard
+ *
+ * Given a rows x cols binary matrix filled with 0's and 1's, find the largest rectangle
+ * containing only 1's and return its area.
+ */
+
+/**
+ * @param {character[][]} matrix
+ * @return {number}
+ */
+var maximalRectangle = function(matrix) {
+  if (!matrix?.length) return 0;
+  let maxArea = 0;
+
+  for (let i = 0; i < matrix.length; i++) {
+    for (let j = 0; j < matrix[0].length; j++) {
+      if (matrix[i][j] === '1') {
+        let minWidth = matrix[0].length;
+
+        for (let k = i; k < matrix.length && matrix[k][j] === '1'; k++) {
+          let width = 0;
+
+          while (width < minWidth && j + width < matrix[0].length && matrix[k][j + width] === '1') {
+            width++;
+          }
+
+          minWidth = Math.min(minWidth, width);
+          maxArea = Math.max(maxArea, minWidth * (k - i + 1));
+        }
+      }
+    }
+  }
+
+  return maxArea;
+};