Add solution #699

Author: JoshCrozier

0699-falling-squares.js

@@ -0,0 +1,51 @@
+/**
+ * 699. Falling Squares
+ * https://leetcode.com/problems/falling-squares/
+ * Difficulty: Hard
+ *
+ * There are several squares being dropped onto the X-axis of a 2D plane.
+ *
+ * You are given a 2D integer array positions where positions[i] = [lefti, sideLengthi]
+ * represents the ith square with a side length of sideLengthi that is dropped with its
+ * left edge aligned with X-coordinate lefti.
+ *
+ * Each square is dropped one at a time from a height above any landed squares. It then
+ * falls downward (negative Y direction) until it either lands on the top side of another
+ * square or on the X-axis. A square brushing the left/right side of another square does
+ * not count as landing on it. Once it lands, it freezes in place and cannot be moved.
+ *
+ * After each square is dropped, you must record the height of the current tallest stack
+ * of squares.
+ *
+ * Return an integer array ans where ans[i] represents the height described above after
+ * dropping the ith square.
+ */
+
+/**
+ * @param {number[][]} positions
+ * @return {number[]}
+ */
+var fallingSquares = function(positions) {
+  const map = new Map();
+  const result = [];
+  let max = 0;
+
+  for (const [left, side] of positions) {
+    const right = left + side;
+    let height = 0;
+
+    for (const [start, [i, n]] of map) {
+      const end = start + i;
+      if (right > start && left < end) {
+        height = Math.max(height, n);
+      }
+    }
+
+    height += side;
+    map.set(left, [side, height]);
+    max = Math.max(max, height);
+    result.push(max);
+  }
+
+  return result;
+};

README.md

@@ -528,6 +528,7 @@
 696|[Count Binary Substrings](./0696-count-binary-substrings.js)|Easy|
 697|[Degree of an Array](./0697-degree-of-an-array.js)|Easy|
 698|[Partition to K Equal Sum Subsets](./0698-partition-to-k-equal-sum-subsets.js)|Medium|
+699|[Falling Squares](./0699-falling-squares.js)|Hard|
 700|[Search in a Binary Search Tree](./0700-search-in-a-binary-search-tree.js)|Easy|
 701|[Insert into a Binary Search Tree](./0701-insert-into-a-binary-search-tree.js)|Medium|
 703|[Kth Largest Element in a Stream](./0703-kth-largest-element-in-a-stream.js)|Easy|