Given a binary tree root and an integer target, delete all the leaf nodes with value target.
Note that once you delete a leaf node with value target, if it's parent node becomes a leaf node and has the value target, it should also be deleted (you need to continue doing that until you can't).
Example 1:
Input: root = [1,2,3,2,null,2,4], target = 2 Output: [1,null,3,null,4] Explanation: Leaf nodes in green with value (target = 2) are removed (Picture in left). After removing, new nodes become leaf nodes with value (target = 2) (Picture in center).
Example 2:
Input: root = [1,3,3,3,2], target = 3 Output: [1,3,null,null,2]
Example 3:
Input: root = [1,2,null,2,null,2], target = 2 Output: [1] Explanation: Leaf nodes in green with value (target = 2) are removed at each step.
Example 4:
Input: root = [1,1,1], target = 1 Output: []
Example 5:
Input: root = [1,2,3], target = 1 Output: [1,2,3]
Constraints:
1 <= target <= 1000- The given binary tree will have between
1and3000nodes. - Each node's value is between
[1, 1000].
struct Solution;
use rustgym_util::*;
trait Postorder {
fn postorder(self, target: i32) -> Self;
}
impl Postorder for TreeLink {
fn postorder(self, target: i32) -> Self {
if let Some(node) = self {
let val = node.borrow().val;
let left = node.borrow_mut().left.take();
let right = node.borrow_mut().right.take();
let left = left.postorder(target);
let right = right.postorder(target);
if left.is_none() && right.is_none() && val == target {
None
} else {
tree!(val, left, right)
}
} else {
None
}
}
}
impl Solution {
fn remove_leaf_nodes(root: TreeLink, target: i32) -> TreeLink {
root.postorder(target)
}
}
#[test]
fn test() {
let root = tree!(1, tree!(2, tree!(2), None), tree!(3, tree!(2), tree!(4)));
let target = 2;
let res = tree!(1, None, tree!(3, None, tree!(4)));
assert_eq!(Solution::remove_leaf_nodes(root, target), res);
let root = tree!(1, tree!(3, tree!(3), tree!(2)), tree!(3));
let target = 3;
let res = tree!(1, tree!(3, None, tree!(2)), None);
assert_eq!(Solution::remove_leaf_nodes(root, target), res);
let root = tree!(1, tree!(2, tree!(2, tree!(2), None), None), None);
let target = 2;
let res = tree!(1);
assert_eq!(Solution::remove_leaf_nodes(root, target), res);
}