LCA.java

class Solution {
  TreeNode answer;
  public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
      this.answer = new TreeNode(-1);
      LCA(root, p, q);
      return this.answer;
  }
  
  public boolean LCA(TreeNode root, TreeNode p, TreeNode q){
      if(root.right == null && root.left == null){//leaf
          if(root.val == p.val || root.val == q.val) return true;
          return false;
      }
      boolean ansL = false;
      boolean ansR = false;
      if(root.left != null){//check right if possible
          ansL = LCA(root.left, p, q);
      }
      if(root.right != null){//check left if possible
          ansR = LCA(root.right, p, q);
      }
      /*check if root contains wanted value and any of 
      left or right branches contains other val*/
      if((root.val == p.val || root.val == q.val) && (ansL || ansR)){
          this.answer = root;
      }
      /*Check if R and L descedants of node contain values wanted*/
      if(ansL && ansR){
          this.answer = root;
      }
      if(root.val == p.val || root.val == q.val) {
          return true;
      }
      return (ansL || ansR);
  }
}