Lowest Common Ancestor III

/**
 * Definition of TreeNode:
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left, right;
 *     public TreeNode(int val) {
 *         this.val = val;
 *         this.left = this.right = null;
 *     }
 * }
 */
public class Solution {
    /**
     * @param root The root of the binary tree.
     * @param A and B two nodes
     * @return: Return the LCA of the two nodes.
     */
    private class ResultType {
        TreeNode node;
        boolean isAExist;
        boolean isBExist;
        public ResultType(TreeNode node, boolean isAExist, boolean isBExist) {
            this.node = node;
            this.isAExist = isAExist;
            this.isBExist = isBExist;
        }
    }
    public TreeNode lowestCommonAncestor3(TreeNode root, TreeNode A, TreeNode B) {
        // write your code here
        ResultType node = findLCA(root, A, B);
        if (node.isAExist && node.isBExist) {
            return node.node;
        }
        return null;
    }
    private ResultType findLCA(TreeNode root, TreeNode A, TreeNode B) {
        if (root == null) {
            return new ResultType(null, false, false);
        }

        ResultType left = findLCA(root.left, A, B);
        ResultType right = findLCA(root.right, A, B);

        boolean isAExist = left.isAExist || right.isAExist || root == A;
        boolean isBExist = left.isBExist || right.isBExist || root == B;
        
        if (root == A || root == B) {
            return new ResultType(root, isAExist, isBExist);
        }

        if (left.node != null && right.node != null) {
            return new ResultType(root, isAExist, isBExist);
        }

        if (left.node != null) {
            return new ResultType(left.node, isAExist, isBExist);
        }

        if (right.node != null) {
            return new ResultType(right.node, isAExist, isBExist);
        }

        return new ResultType(null, isAExist, isBExist);
    }
}