958. Check Completeness of a Binary Tree

Version #2 BFS[TODO]


Version #1 DFS

98.36 
class Solution {
    int count;
    public boolean isCompleteTree(TreeNode root) {
        count = getCount(root);
        return validate(root, 1);
    }
   
    private boolean validate(TreeNode node, int id) {
        if (node == null) return true;
        if (id > count) return false;
        return validate(node.left, id * 2) && validate(node.right, id * 2 + 1);
    }
   
   
    private int getCount(TreeNode node) {
        if (node == null) return 0;
        return 1 + getCount(node.left) + getCount(node.right);
    }
}