Add solution #558

Author: JoshCrozier

README.md

@@ -442,6 +442,7 @@
 554|[Brick Wall](./0554-brick-wall.js)|Medium|
 556|[Next Greater Element III](./0556-next-greater-element-iii.js)|Medium|
 557|[Reverse Words in a String III](./0557-reverse-words-in-a-string-iii.js)|Easy|
+558|[Logical OR of Two Binary Grids Represented as Quad-Trees](./0558-logical-or-of-two-binary-grids-represented-as-quad-trees.js)|Medium|
 560|[Subarray Sum Equals K](./0560-subarray-sum-equals-k.js)|Medium|
 563|[Binary Tree Tilt](./0563-binary-tree-tilt.js)|Easy|
 565|[Array Nesting](./0565-array-nesting.js)|Medium|

solutions/0558-logical-or-of-two-binary-grids-represented-as-quad-trees.js

@@ -0,0 +1,71 @@
+/**
+ * 558. Logical OR of Two Binary Grids Represented as Quad-Trees
+ * https://leetcode.com/problems/logical-or-of-two-binary-grids-represented-as-quad-trees/
+ * Difficulty: Medium
+ *
+ * A Binary Matrix is a matrix in which all the elements are either 0 or 1.
+ *
+ * Given quadTree1 and quadTree2. quadTree1 represents a n * n binary matrix and quadTree2
+ * represents another n * n binary matrix.
+ *
+ * Return a Quad-Tree representing the n * n binary matrix which is the result of logical
+ * bitwise OR of the two binary matrixes represented by quadTree1 and quadTree2.
+ *
+ * Notice that you can assign the value of a node to True or False when isLeaf is False, and
+ * both are accepted in the answer.
+ *
+ * A Quad-Tree is a tree data structure in which each internal node has exactly four children.
+ * Besides, each node has two attributes:
+ * - val: True if the node represents a grid of 1's or False if the node represents a grid of 0's.
+ * - isLeaf: True if the node is leaf node on the tree or False if the node has the four children.
+ * class Node {
+ *     public boolean val;
+ *     public boolean isLeaf;
+ *     public Node topLeft;
+ *     public Node topRight;
+ *     public Node bottomLeft;
+ *     public Node bottomRight;
+ * }.
+ *
+ * We can construct a Quad-Tree from a two-dimensional area using the following steps:
+ * 1. If the current grid has the same value (i.e all 1's or all 0's) set isLeaf True and set val to
+ *    the value of the grid and set the four children to Null and stop.
+ * 2. If the current grid has different values, set isLeaf to False and set val to any value and
+ *    divide the current grid into four sub-grids as shown in the photo.
+ * 3. Recurse for each of the children with the proper sub-grid.
+ */
+
+/**
+ * // Definition for a QuadTree node.
+ * function _Node(val,isLeaf,topLeft,topRight,bottomLeft,bottomRight) {
+ *    this.val = val;
+ *    this.isLeaf = isLeaf;
+ *    this.topLeft = topLeft;
+ *    this.topRight = topRight;
+ *    this.bottomLeft = bottomLeft;
+ *    this.bottomRight = bottomRight;
+ * };
+ */
+
+/**
+ * @param {_Node} quadTree1
+ * @param {_Node} quadTree2
+ * @return {_Node}
+ */
+var intersect = function(quadTree1, quadTree2) {
+  if (quadTree1.isLeaf) return quadTree1.val ? quadTree1 : quadTree2;
+  if (quadTree2.isLeaf) return quadTree2.val ? quadTree2 : quadTree1;
+
+  const topLeft = intersect(quadTree1.topLeft, quadTree2.topLeft);
+  const topRight = intersect(quadTree1.topRight, quadTree2.topRight);
+  const bottomLeft = intersect(quadTree1.bottomLeft, quadTree2.bottomLeft);
+  const bottomRight = intersect(quadTree1.bottomRight, quadTree2.bottomRight);
+
+  if (topLeft.isLeaf && topRight.isLeaf && bottomLeft.isLeaf && bottomRight.isLeaf
+      && topLeft.val === topRight.val && topRight.val === bottomLeft.val
+      && bottomLeft.val === bottomRight.val) {
+    return new _Node(topLeft.val, true, null, null, null, null);
+  }
+
+  return new _Node(false, false, topLeft, topRight, bottomLeft, bottomRight);
+};