binary-tree-right-side-view

binary-tree-right-side-view/sol.go

@@ -0,0 +1,45 @@
+package main
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func rightSideView(root *TreeNode) (out []int) {
+	if root == nil {
+		return
+	}
+	for stack := []*TreeNode{root}; len(stack) != 0; {
+		top := stack[len(stack)-1]
+		if len(stack) > len(out) {
+			out = append(out, top.Val)
+		}
+		if top.Right != nil {
+			stack = append(stack, top.Right)
+		} else if top.Left != nil {
+			stack = append(stack, top.Left)
+		} else {
+			stack = stack[:len(stack)-1]
+			if len(stack) != 0 {
+				new_top := stack[len(stack)-1]
+				// Easiest way to DFS by modification of tree.
+				// There was no requirement to keep it intact ¯\_(ツ)_/¯.
+				if new_top.Right == top {
+					new_top.Right = nil
+				} else {
+					new_top.Left = nil
+				}
+			}
+		}
+	}
+	return
+}