Create 987-vertical-order-traversal-of-a-binary-tree.js

Author: everthis

987-vertical-order-traversal-of-a-binary-tree.js

@@ -0,0 +1,32 @@
+/**
+ * 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[][]}
+ */
+const verticalTraversal = function(root) {
+  const arr = []
+  helper(root, 0, 0, arr)
+  arr.sort((a, b) => a[0] - b[0] || b[1] - a[1] || a[2] - b[2])
+  const res = new Map()
+
+  for(let [x, y, val] of arr) {
+    if(!res.has(x)) res.set(x, [])
+    res.get(x).push(val)
+  }
+  return [...res.values()]
+};
+
+function helper(node, x, y, arr) {
+  if(node) {
+    helper(node.left, x - 1, y - 1, arr)
+    arr.push([x, y, node.val])
+    helper(node.right, x  + 1, y - 1, arr)
+  }
+}