Check if all Leaf nodes are at same level.

Problem Statement:
     Check if all leaves of a Binary Tree at the same level.


Solution:

The below recursive solution checks if the tree has all leaves at the same level or not.

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/** * Check if Binary tree has all nodes at the same level * @param root: root node * @param previousLevel : level of 1st leaf encoutered , initial value = 0 passed * @param currentLevel : level of any current node , initial value = 0 passed * @return true , iff all nodes are at same level */ public boolean isLevelSame(Node root , int previousLevel , int currentLevel ) { if(root==null) return true; if(root.left == null && root.right == null) { // First Leaf Encoutered , saved the level of 1st leaf if(previousLevel == 0) { previousLevel = currentLevel ; return true ; } // all Subsequent leaves should be equal to the first leaf encoutered return (previousLevel == currentLevel) ; } // checking for left and right sub tree of every node return isLevelSame(root.left , previousLevel , currentLevel + 1) && isLevelSame(root.right , previousLevel , currentLevel + 1) ; }