Binary Tree paths and add helper for deserilze the string to node

Author: nch3ng

Binary Tree Paths/Solution.rb

@@ -0,0 +1,50 @@
+require '../helper.rb'
+
+# @param {TreeNode} root
+# @return {String[]}
+def binary_tree_paths(root)
+   
+  return [] if root.nil?
+  parent_path = Hash.new
+  s=[];
+  paths=[];
+  
+  s.push(root)
+  
+  until s.empty?
+
+    r=s.pop();
+    #puts r.val
+    #puts ''
+    p=''
+    if parent_path[r].nil?
+      p = r.val.to_s
+    else
+      #puts parent_path[r]
+      #puts r.val
+      p = "#{parent_path[r]}->#{r.val}"
+    end
+    
+    #puts p
+    
+    if r.left.nil? && r.right.nil?
+      #puts 'Its leafnode'
+      paths.push(p)
+    end
+    
+    if !r.right.nil?
+      s.push(r.right)
+      parent_path[r.right]=p.to_s
+    end
+
+    if !r.left.nil?
+      s.push(r.left)
+      parent_path[r.left]=p.to_s
+    end
+  end
+  paths
+end
+
+data = [1,2,3,4,nil,nil,5]
+node = deserialize(data)
+print binary_tree_paths(node)

helper.rb

@@ -0,0 +1,35 @@
+# Definition for a binary tree node.
+class TreeNode
+  attr_accessor :val, :left, :right
+  def initialize(val)
+    @val = val
+    @left, @right = nil, nil
+  end
+end
+
+# Deserialize string to root object
+def deserialize(data)
+    return data if data.nil?
+    q=[]
+    
+    root = TreeNode.new(data.shift)
+    q.push(root)
+  
+    until data.empty?
+        t = q.shift
+        l = data.shift
+        r = data.shift
+  
+    unless l.nil?
+        t.left = TreeNode.new(l)
+        q.push(t.left)
+    end
+    
+    unless r.nil?
+        t.right = TreeNode.new(r)
+        q.push(t.right)
+    end
+    
+  end
+  root
+end