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| class Solution {
public TreeNode deleteNode(TreeNode root, int key) {
if (root == null) {
return null;
}
if (key < root.val) {
root.left = deleteNode(root.left, key);
} else if (key > root.val) {
root.right = deleteNode(root.right, key);
} else {
if (root.left == null && root.right == null) {
root = null;
} else if (root.left != null && root.right == null) {
root = root.left;
} else if (root.left == null && root.right != null) {
root = root.right;
} else {
TreeNode predecessor = findPredecessor(root);
root.val = predecessor.val;
root.left = deleteNode(root.left, root.val);
}
}
return root;
}
private TreeNode findPredecessor(TreeNode node) {
node = node.left;
while (node.right != null) {
node = node.right;
}
return node;
}
}
|
定义递归函数的功能就是给定一个树, 删除我们指定值对应的node然后返回这个树的root, 如果树中没有node等于指定的值, 什么也不做.
时间复杂度: O(n) 可能是skewed tree
空间复杂度: O(n) 可能是skewed tree
