Create 993. Cousins in Binary Tree

Author: haibarawu

993. Cousins in Binary Tree

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+/*
+In a binary tree, the root node is at depth 0, and children of each depth k node are at depth k+1.
+
+Two nodes of a binary tree are cousins if they have the same depth, but have different parents.
+
+We are given the root of a binary tree with unique values, and the values x and y of two different nodes in the tree.
+
+Return true if and only if the nodes corresponding to the values x and y are cousins.
+
+Example:
+
+     6
+   /   \
+  3     5
+ / \   / \
+7   8 1   3
+
+Say two node be 7 and 1, result is TRUE.
+Say two nodes are 3 and 5, result is FALSE.
+Say two nodes are 7 and 5, result is FALSE.
+*/
+
+
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+ 
+class Solution {
+    public int x_level;
+    public TreeNode x_parent;
+    public int y_level;
+    public TreeNode y_parent;
+    
+    public boolean isCousins(TreeNode root, int x, int y) {
+        search(root, x, y, 0, null);
+        
+        return x_level == y_level && x_parent != y_parent;
+    }
+    
+    public void search(TreeNode root, int x, int y, int level, TreeNode parent)
+    {
+        if(root== null) return ;
+        if(root.val == x)
+        {
+            x_level = level;
+            x_parent = parent;
+        }
+        if(root.val == y)
+        {
+            y_level = level;
+            y_parent = parent;
+        }
+        search(root.left,x,y,level+1,root);
+        search(root.right,x,y,level+1,root);
+    }
+}