力扣上的一道简单的题，但不知道哪里出问题了

/**

Definition for a binary tree node.
public class TreeNode {
```
int val;
```
```
TreeNode left;
```
```
TreeNode right;
```
```
TreeNode() {}
```
```
TreeNode(int val) { this.val = val; }
```

TreeNode(int val, TreeNode left, TreeNode right) {

```
    this.val = val;
```
```
    this.left = left;
```
```
    this.right = right;
```
```
}
```
}

/
class Solution {
public boolean isSameTree(TreeNode p, TreeNode q) {

  if(p==null&&q==null)
    return true;
  else if(p==null||q==null)
    return false;
  else if(p.val!=q.val)
  {
      return false;
  }
  if (isSameTree(p.left,q.left)&&isSameTree(p.right,q.right)){
      return true;
  }
  return true;

}
}

最后一个

return false;