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@@ -0,0 +1,71 @@
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+// Definition for a binary tree node.
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+struct TreeNode {
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+ int val;
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+ TreeNode *left;
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+ TreeNode *right;
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+ TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
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+};
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+
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+/* BEGIN */
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+
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+#include <cstdio>
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+
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+class Solution {
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+public:
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+ TreeNode* insertIntoBST(TreeNode* root, int val) {
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+ if (root == nullptr) {
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+ return new TreeNode(val); // "new" to avoid freeing memory
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+ }
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+ if (val <= root->val) {
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+ root->left = insertIntoBST(root->left, val);
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+ } else {
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+ root->right = insertIntoBST(root->right, val);
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+ }
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+ return root;
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+ }
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+};
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+
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+/* END */
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+
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+#include <queue>
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+
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+using std::queue;
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+
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+void print_tree(TreeNode *root) {
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+ if (root == nullptr) {
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+ printf("null\n");
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+ return;
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+ }
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+ queue<TreeNode *> q;
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+ q.push(root);
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+ TreeNode *curr = nullptr;
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+ int cnt = q.size();
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+ while (q.size() != 0) {
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+ curr = q.front();
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+ q.pop();
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+ cnt--;
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+ printf("%d ", curr->val);
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+ if (curr->left != nullptr) {
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+ q.push(curr->left);
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+ }
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+ if (curr->right != nullptr) {
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+ q.push(curr->right);
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+ }
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+ if (cnt == 0) {
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+ cnt = q.size();
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+ printf("\n");
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+ }
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+ }
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+}
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+
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+int main() {
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+ TreeNode n1(1), n2(2), n3(3), n4(4), n7(7);
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+ n2.left = &n1;
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+ n2.right = &n3;
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+ n4.left = &n2;
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+ n4.right = &n7;
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+ TreeNode *root = &n4;
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+ print_tree(root);
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+ root = (new Solution())->insertIntoBST(root, 5);
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+ print_tree(root);
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+}
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