Add solution #314

Author: JoshCrozier

README.md

@@ -302,6 +302,7 @@
 311|[Sparse Matrix Multiplication](./solutions/0311-sparse-matrix-multiplication.js)|Medium|
 312|[Burst Balloons](./solutions/0312-burst-balloons.js)|Hard|
 313|[Super Ugly Number](./solutions/0313-super-ugly-number.js)|Medium|
+314|[Binary Tree Vertical Order Traversal](./solutions/0314-binary-tree-vertical-order-traversal.js)|Medium|
 315|[Count of Smaller Numbers After Self](./solutions/0315-count-of-smaller-numbers-after-self.js)|Hard|
 316|[Remove Duplicate Letters](./solutions/0316-remove-duplicate-letters.js)|Medium|
 318|[Maximum Product of Word Lengths](./solutions/0318-maximum-product-of-word-lengths.js)|Medium|

solutions/0314-binary-tree-vertical-order-traversal.js

@@ -0,0 +1,53 @@
+/**
+ * 314. Binary Tree Vertical Order Traversal
+ * https://leetcode.com/problems/binary-tree-vertical-order-traversal/
+ * Difficulty: Medium
+ *
+ * Given the root of a binary tree, return the vertical order traversal of its nodes' values.
+ * (i.e., from top to bottom, column by column).
+ *
+ * If two nodes are in the same row and column, the order should be from left to right.
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[][]}
+ */
+var verticalOrder = function(root) {
+  if (!root) return [];
+
+  const columns = new Map();
+  const queue = [[root, 0]];
+  let minCol = 0;
+  let maxCol = 0;
+
+  while (queue.length) {
+    const [node, col] = queue.shift();
+    if (!columns.has(col)) columns.set(col, []);
+    columns.get(col).push(node.val);
+
+    if (node.left) {
+      queue.push([node.left, col - 1]);
+      minCol = Math.min(minCol, col - 1);
+    }
+    if (node.right) {
+      queue.push([node.right, col + 1]);
+      maxCol = Math.max(maxCol, col + 1);
+    }
+  }
+
+  const result = [];
+  for (let col = minCol; col <= maxCol; col++) {
+    if (columns.has(col)) result.push(columns.get(col));
+  }
+
+  return result;
+};