1325. Delete Leaves With a Given Value

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class Solution {
    public TreeNode removeLeafNodes(TreeNode root, int target) {
        return dfs(root, target);
    }

    private TreeNode dfs(TreeNode node, int target) {
        // left -> right -> root

        if (node == null) {
            return null;
        }

        node.left = dfs(node.left, target);
        node.right = dfs(node.right, target);

        if (node.left == null && node.right == null && node.val == target) {
            return null;
        }
        return node;
    }
}

后序遍历，注意在处理完左右子树后再处理当前节点。

References

1325. Delete Leaves With a Given Value