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69. Sqrtx

Math Binary Search

Problem - Sqrtx

Easy

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.

  • For example, do not use pow(x, 0.5) in c++ or x ** 0.5 in python.

 

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 2.82842..., and since we round it down to the nearest integer, 2 is returned.

 

Constraints:

  • 0 <= x <= 231 - 1

Solutions

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class Solution:
    def mySqrt(self, x: int) -> int:
        left, right = 0, x
        while right > left:
            mid = (left + right + 1) // 2
            if mid > x // mid:
                right = mid - 1
            else:
                left = mid
        return left

Submission Stats:

  • Runtime: 0 ms (100.00%)
  • Memory: 18 MB (10.83%)