Create 0103-binary-tree-zigzag-level-order-traversal.kt

Author: a93a

kotlin/0103-binary-tree-zigzag-level-order-traversal.kt

@@ -0,0 +1,41 @@
+/**
+ * Example:
+ * var ti = TreeNode(5)
+ * var v = ti.`val`
+ * Definition for a binary tree node.
+ * class TreeNode(var `val`: Int) {
+ *     var left: TreeNode? = null
+ *     var right: TreeNode? = null
+ * }
+ */
+class Solution {
+    fun zigzagLevelOrder(root: TreeNode?): List<List<Int>> {
+
+        val res = ArrayList<ArrayList<Int>>()
+        root?: return res
+
+        val q = ArrayDeque<TreeNode?>()
+        var left = true
+
+        q.add(root)
+
+        while(q.isNotEmpty()) {
+            val s = q.size
+            val temp = ArrayList<Int>()
+            repeat (s) {
+                val x = q.poll()!!
+                if(x.left != null) q.add(x.left)
+                if(x.right != null) q.add(x.right)
+                if(left) temp.add(x.value)
+                else temp.add(0, x.value)
+            }
+            res.add(temp)
+            left = !left
+        }
+
+        return res
+    }
+
+    val TreeNode.value 
+        get() = this.`val`
+}