Add a Solution for Sqrt(x) (LeetCode Problem 69)

dsa-solutions/lc-solutions/0000-0099/0069-SqrtX.md

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+---
+id: sqrt-x
+title: Sqrt(x) (LeetCode)
+difficulty: Easy
+sidebar_label: 0069-SqrtX
+topics:
+  - Math
+  - Binary Search
+---
+
+
+## Problem Description
+
+| Problem Statement | Solution Link | LeetCode Profile |
+| :---------------- | :------------ | :--------------- |
+| [Merge Two Sorted Lists](https://leetcode.com/problems/sqrtx/) | [Merge Two Sorted Lists Solution on LeetCode](https://leetcode.com/problems/sqrtx/solutions/) |  [VijayShankerSharma](https://leetcode.com/u/darkknight648/) |
+
+## Problem Description
+
+Given a non-negative integer `x`, return the square root of `x` rounded down to the nearest integer. The returned integer should be non-negative as well.
+
+You must not use any built-in exponent function or operator.
+
+### Examples
+
+#### Example 1:
+
+- **Input:** `x = 4`
+- **Output:** `2`
+- **Explanation:** The square root of 4 is 2, so we return 2.
+
+#### Example 2:
+
+- **Input:** `x = 8`
+- **Output:** `2`
+- **Explanation:** The square root of 8 is approximately 2.82842..., and since we round it down to the nearest integer, 2 is returned.
+
+### Constraints:
+
+- `0 <= x <= 2^31 - 1`
+
+### Approach
+
+To find the square root of a non-negative integer `x` without using built-in functions, we can use binary search within the range `[0, x]`.
+
+1. Initialize variables `left` and `right` to represent the search range `[0, x]`.
+2. Perform binary search within this range, updating the `mid` value as `(left + right) / 2`.
+3. If `mid * mid` is greater than `x`, update `right` to `mid - 1`.
+4. If `mid * mid` is less than or equal to `x`, update `left` to `mid + 1`.
+5. Repeat steps 2-4 until `left` is greater than `right`.
+6. Return the value of `right`, which represents the largest integer whose square is less than or equal to `x`.
+
+### Solution Code
+
+#### Python
+
+```
+class Solution(object):
+    def mySqrt(self, x):
+        if x < 2:
+            return x
+        left, right = 1, x
+        while left <= right:
+            mid = (left + right) // 2
+            if mid * mid == x:
+                return mid
+            elif mid * mid < x:
+                left = mid + 1
+            else:
+                right = mid - 1
+        return right
+```
+
+#### C++
+
+```
+class Solution {
+public:
+    int mySqrt(int x) {
+        if (x == 0) {
+            return 0;
+        }
+
+        long left = 1, right = x;
+        while (left <= right) {
+            long mid = (left + right) / 2;
+            if (mid * mid == x) {
+                return mid;
+            } else if (mid * mid < x) {
+                left = mid + 1;
+            } else {
+                right = mid - 1;
+            }
+        }
+
+        return right;
+    }
+};
+```
+
+#### Java
+
+```
+class Solution {
+    public int mySqrt(int x) {
+        if (x == 0) {
+            return 0;
+        }
+
+        long left = 1, right = x;
+        while (left <= right) {
+            long mid = (left + right) / 2;
+            if (mid * mid == x) {
+                return (int)mid;
+            } else if (mid * mid < x) {
+                left = mid + 1;
+            } else {
+                right = mid - 1;
+            }
+        }
+
+        return (int)right;
+    }
+}
+```
+
+### Conclusion
+
+The "Sqrt(x)" problem can be efficiently solved using binary search within the range `[0, x]`. The provided solution code implements this approach in Python, C++, and Java, providing an optimal solution to the problem.