Binary Trees

// leetcode 965 =================================

class Solution {
    public boolean checkIfUnivalued(TreeNode root, int OGRootValue){
        if(root == null){
            return true;
        }

        if(root.val != OGRootValue){
            return false;
        }

        boolean isLeftUnivalued = checkIfUnivalued(root.left, OGRootValue);
        
        boolean isRightUnivalued = checkIfUnivalued(root.right, OGRootValue);

        return isRightUnivalued && isLeftUnivalued;
    }

    public boolean isUnivalTree(TreeNode root) {
        int rootValue = root.val;

        return checkIfUnivalued(root, rootValue); 
    }
}


// leetcode 226 =========================================================

class Solution {
    public TreeNode invertTree(TreeNode root) {
        if(root == null){
            return root;
        }

        // inverting current position
        TreeNode temp = root.left;
        root.left = root.right;
        root.right = temp;

        invertTree(root.left);
        invertTree(root.right);

        return root;
    }
}

// Solution 2 =================================================
class Solution {
    public TreeNode invertTree(TreeNode root) {
        if(root == null){
            return root;
        }

        // inverting current position
        TreeNode temp = root.right;
        
        root.right = invertTree(root.left);
        root.left = invertTree(temp);

        return root;
    }
}


// leetcode 1325 ==================================================

class Solution {
    public TreeNode removeLeafNodes(TreeNode root, int target) {
        if(root == null){
            return root;
        }

        root.left = removeLeafNodes(root.left, target);
        root.right = removeLeafNodes(root.right, target);

        if(root.left == null && root.right == null && root.val == target){
            return null;
        }

        return root;
    }
}