|
| 1 | +## 1. Recursion |
| 2 | + |
| 3 | +::tabs-start |
| 4 | + |
| 5 | +```python |
| 6 | +# Definition for a binary tree node. |
| 7 | +# class TreeNode: |
| 8 | +# def __init__(self, val=0, left=None, right=None): |
| 9 | +# self.val = val |
| 10 | +# self.left = left |
| 11 | +# self.right = right |
| 12 | +class Solution: |
| 13 | + def insertIntoBST(self, root: Optional[TreeNode], val: int) -> Optional[TreeNode]: |
| 14 | + if not root: |
| 15 | + return TreeNode(val) |
| 16 | + |
| 17 | + if val > root.val: |
| 18 | + root.right = self.insertIntoBST(root.right, val) |
| 19 | + else: |
| 20 | + root.left = self.insertIntoBST(root.left, val) |
| 21 | + |
| 22 | + return root |
| 23 | +``` |
| 24 | + |
| 25 | +```java |
| 26 | +/** |
| 27 | + * Definition for a binary tree node. |
| 28 | + * public class TreeNode { |
| 29 | + * int val; |
| 30 | + * TreeNode left; |
| 31 | + * TreeNode right; |
| 32 | + * TreeNode() {} |
| 33 | + * TreeNode(int val) { this.val = val; } |
| 34 | + * TreeNode(int val, TreeNode left, TreeNode right) { |
| 35 | + * this.val = val; |
| 36 | + * this.left = left; |
| 37 | + * this.right = right; |
| 38 | + * } |
| 39 | + * } |
| 40 | + */ |
| 41 | +public class Solution { |
| 42 | + public TreeNode insertIntoBST(TreeNode root, int val) { |
| 43 | + if (root == null) { |
| 44 | + return new TreeNode(val); |
| 45 | + } |
| 46 | + |
| 47 | + if (val > root.val) { |
| 48 | + root.right = insertIntoBST(root.right, val); |
| 49 | + } else { |
| 50 | + root.left = insertIntoBST(root.left, val); |
| 51 | + } |
| 52 | + |
| 53 | + return root; |
| 54 | + } |
| 55 | +} |
| 56 | +``` |
| 57 | + |
| 58 | +```cpp |
| 59 | +/** |
| 60 | + * Definition for a binary tree node. |
| 61 | + * struct TreeNode { |
| 62 | + * int val; |
| 63 | + * TreeNode *left; |
| 64 | + * TreeNode *right; |
| 65 | + * TreeNode() : val(0), left(nullptr), right(nullptr) {} |
| 66 | + * TreeNode(int x) : val(x), left(nullptr), right(nullptr) {} |
| 67 | + * TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {} |
| 68 | + * }; |
| 69 | + */ |
| 70 | +class Solution { |
| 71 | +public: |
| 72 | + TreeNode* insertIntoBST(TreeNode* root, int val) { |
| 73 | + if (!root) { |
| 74 | + return new TreeNode(val); |
| 75 | + } |
| 76 | + |
| 77 | + if (val > root->val) { |
| 78 | + root->right = insertIntoBST(root->right, val); |
| 79 | + } else { |
| 80 | + root->left = insertIntoBST(root->left, val); |
| 81 | + } |
| 82 | + |
| 83 | + return root; |
| 84 | + } |
| 85 | +}; |
| 86 | +``` |
| 87 | + |
| 88 | +```javascript |
| 89 | +/** |
| 90 | + * Definition for a binary tree node. |
| 91 | + * class TreeNode { |
| 92 | + * constructor(val = 0, left = null, right = null) { |
| 93 | + * this.val = val; |
| 94 | + * this.left = left; |
| 95 | + * this.right = right; |
| 96 | + * } |
| 97 | + * } |
| 98 | + */ |
| 99 | +class Solution { |
| 100 | + /** |
| 101 | + * @param {TreeNode} root |
| 102 | + * @param {number} val |
| 103 | + * @return {TreeNode} |
| 104 | + */ |
| 105 | + insertIntoBST(root, val) { |
| 106 | + if (!root) { |
| 107 | + return new TreeNode(val); |
| 108 | + } |
| 109 | + |
| 110 | + if (val > root.val) { |
| 111 | + root.right = this.insertIntoBST(root.right, val); |
| 112 | + } else { |
| 113 | + root.left = this.insertIntoBST(root.left, val); |
| 114 | + } |
| 115 | + |
| 116 | + return root; |
| 117 | + } |
| 118 | +} |
| 119 | +``` |
| 120 | + |
| 121 | +::tabs-end |
| 122 | + |
| 123 | +### Time & Space Complexity |
| 124 | + |
| 125 | +* Time complexity: $O(h)$ |
| 126 | +* Space complexity: $O(h)$ for the recursion stack. |
| 127 | + |
| 128 | +> Where $h$ is the height of the given binary search tree. |
| 129 | +
|
| 130 | +--- |
| 131 | + |
| 132 | +## 2. Iteration |
| 133 | + |
| 134 | +::tabs-start |
| 135 | + |
| 136 | +```python |
| 137 | +# Definition for a binary tree node. |
| 138 | +# class TreeNode: |
| 139 | +# def __init__(self, val=0, left=None, right=None): |
| 140 | +# self.val = val |
| 141 | +# self.left = left |
| 142 | +# self.right = right |
| 143 | +class Solution: |
| 144 | + def insertIntoBST(self, root: Optional[TreeNode], val: int) -> Optional[TreeNode]: |
| 145 | + if not root: |
| 146 | + return TreeNode(val) |
| 147 | + |
| 148 | + cur = root |
| 149 | + while True: |
| 150 | + if val > cur.val: |
| 151 | + if not cur.right: |
| 152 | + cur.right = TreeNode(val) |
| 153 | + return root |
| 154 | + cur = cur.right |
| 155 | + else: |
| 156 | + if not cur.left: |
| 157 | + cur.left = TreeNode(val) |
| 158 | + return root |
| 159 | + cur = cur.left |
| 160 | +``` |
| 161 | + |
| 162 | +```java |
| 163 | +/** |
| 164 | + * Definition for a binary tree node. |
| 165 | + * public class TreeNode { |
| 166 | + * int val; |
| 167 | + * TreeNode left; |
| 168 | + * TreeNode right; |
| 169 | + * TreeNode() {} |
| 170 | + * TreeNode(int val) { this.val = val; } |
| 171 | + * TreeNode(int val, TreeNode left, TreeNode right) { |
| 172 | + * this.val = val; |
| 173 | + * this.left = left; |
| 174 | + * this.right = right; |
| 175 | + * } |
| 176 | + * } |
| 177 | + */ |
| 178 | +public class Solution { |
| 179 | + public TreeNode insertIntoBST(TreeNode root, int val) { |
| 180 | + if (root == null) { |
| 181 | + return new TreeNode(val); |
| 182 | + } |
| 183 | + |
| 184 | + TreeNode cur = root; |
| 185 | + while (true) { |
| 186 | + if (val > cur.val) { |
| 187 | + if (cur.right == null) { |
| 188 | + cur.right = new TreeNode(val); |
| 189 | + return root; |
| 190 | + } |
| 191 | + cur = cur.right; |
| 192 | + } else { |
| 193 | + if (cur.left == null) { |
| 194 | + cur.left = new TreeNode(val); |
| 195 | + return root; |
| 196 | + } |
| 197 | + cur = cur.left; |
| 198 | + } |
| 199 | + } |
| 200 | + } |
| 201 | +} |
| 202 | +``` |
| 203 | + |
| 204 | +```cpp |
| 205 | +/** |
| 206 | + * Definition for a binary tree node. |
| 207 | + * struct TreeNode { |
| 208 | + * int val; |
| 209 | + * TreeNode *left; |
| 210 | + * TreeNode *right; |
| 211 | + * TreeNode() : val(0), left(nullptr), right(nullptr) {} |
| 212 | + * TreeNode(int x) : val(x), left(nullptr), right(nullptr) {} |
| 213 | + * TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {} |
| 214 | + * }; |
| 215 | + */ |
| 216 | +class Solution { |
| 217 | +public: |
| 218 | + TreeNode* insertIntoBST(TreeNode* root, int val) { |
| 219 | + if (!root) { |
| 220 | + return new TreeNode(val); |
| 221 | + } |
| 222 | + |
| 223 | + TreeNode* cur = root; |
| 224 | + while (true) { |
| 225 | + if (val > cur->val) { |
| 226 | + if (!cur->right) { |
| 227 | + cur->right = new TreeNode(val); |
| 228 | + return root; |
| 229 | + } |
| 230 | + cur = cur->right; |
| 231 | + } else { |
| 232 | + if (!cur->left) { |
| 233 | + cur->left = new TreeNode(val); |
| 234 | + return root; |
| 235 | + } |
| 236 | + cur = cur->left; |
| 237 | + } |
| 238 | + } |
| 239 | + } |
| 240 | +}; |
| 241 | +``` |
| 242 | + |
| 243 | +```javascript |
| 244 | +/** |
| 245 | + * Definition for a binary tree node. |
| 246 | + * class TreeNode { |
| 247 | + * constructor(val = 0, left = null, right = null) { |
| 248 | + * this.val = val; |
| 249 | + * this.left = left; |
| 250 | + * this.right = right; |
| 251 | + * } |
| 252 | + * } |
| 253 | + */ |
| 254 | +class Solution { |
| 255 | + /** |
| 256 | + * @param {TreeNode} root |
| 257 | + * @param {number} val |
| 258 | + * @return {TreeNode} |
| 259 | + */ |
| 260 | + insertIntoBST(root, val) { |
| 261 | + if (!root) { |
| 262 | + return new TreeNode(val); |
| 263 | + } |
| 264 | + |
| 265 | + let cur = root; |
| 266 | + while (true) { |
| 267 | + if (val > cur.val) { |
| 268 | + if (!cur.right) { |
| 269 | + cur.right = new TreeNode(val); |
| 270 | + return root; |
| 271 | + } |
| 272 | + cur = cur.right; |
| 273 | + } else { |
| 274 | + if (!cur.left) { |
| 275 | + cur.left = new TreeNode(val); |
| 276 | + return root; |
| 277 | + } |
| 278 | + cur = cur.left; |
| 279 | + } |
| 280 | + } |
| 281 | + } |
| 282 | +} |
| 283 | +``` |
| 284 | + |
| 285 | +::tabs-end |
| 286 | + |
| 287 | +### Time & Space Complexity |
| 288 | + |
| 289 | +* Time complexity: $O(h)$ |
| 290 | +* Space complexity: $O(1)$ extra space. |
| 291 | + |
| 292 | +> Where $h$ is the height of the given binary search tree. |
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