Create convertSortedArrayToBinarySearchTree.cpp

DFS/convertSortedArrayToBinarySearchTree.cpp

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+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+
+// BINARY SEARCH
+
+class Solution
+{
+public:
+    TreeNode *func(vector<int> &nums, int low, int high)
+    {
+        while (low <= high)
+        {
+            int mid = low + (high - low) / 2;
+
+            TreeNode *root = new TreeNode(nums[mid], func(nums, low, mid - 1), func(nums, mid + 1, high));
+
+            // TreeNode *root = new TreeNode(nums[mid]);
+            // root->left = func(nums, low, mid - 1);
+            // root->right = func(nums, mid + 1, high);
+
+            return root;
+        }
+        return nullptr;
+    }
+
+    TreeNode *sortedArrayToBST(vector<int> &nums)
+    {
+        return func(nums, 0, nums.size() - 1);
+    }
+};
+
+// FASTEST SOLUTION
+
+class Solution
+{
+public:
+    TreeNode *sortedArrayToBST(vector<int> &nums)
+    {
+        if (nums.size() < 1)
+            return NULL;
+        int mid = (nums.size() / 2);
+        TreeNode *root = new TreeNode(nums[mid]);
+        vector<int> left(nums.begin(), nums.begin() + mid);
+        vector<int> right(nums.begin() + mid + 1, nums.end());
+        root->left = sortedArrayToBST(left);
+        root->right = sortedArrayToBST(right);
+        return root;
+    }
+};