题解 | #树的子结构#

递归解决，效率不太高，继续优化

/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    public boolean HasSubtree(TreeNode root1, TreeNode root2) {
        if(root1 == null || root2 == null){
            return false;
        }
        
        return HasSubtree(root1, root2, false);
    }
    
        public boolean HasSubtree(TreeNode root1, TreeNode root2, boolean full) {
        if (root2 == null) {
            return true;
        }
        if(root1 == null){
            return false;
        }
        boolean left = false;
        boolean right = false;
        if (root1.val == root2.val) {
            left = HasSubtree(root1.left, root2.left, true);
            right = HasSubtree(root1.right, root2.right, true);
            if (!(left && right)) {
                left = HasSubtree(root1.left, root2, false);
                right = HasSubtree(root1.right, root2, false);
                return left || right;
            }else{
                return true;
            }
        } else {
            if(full)return false;
            left = HasSubtree(root1.left, root2, full);
            right = HasSubtree(root1.right, root2, full);
        }

        return full ? left && right : left || right;
    }
}