Write a function that finds the square root of a given non-negative integer, rounded down to the nearest integer, without using the built-in sqrt() function. For example, the square root of numbers in the range [9, 15] should return 3, and for numbers in the range [16, 24] it should return 4.

Example:

Input: 15
Output: 3

The function should return 3 because: 3^2 = 9, which is less than 15, and 4^2 = 16 exceeds 15.

Constraints:

• The input number will always be non-negative.
• The function should return an integer result that rounds down the square root.

Write a function that finds the square root of a given non-negative integer, rounded down to the nearest integer, without using the built-in sqrt() function. For example, the square root of numbers in the range [9, 15] should return 3, and for numbers in the range [16, 24] it should return 4.

Example:

Input: 15
Output: 3

The function should return 3 because: 3^2 = 9, which is less than 15, and 4^2 = 16 exceeds 15.

Constraints:

• The input number will always be non-negative.
• The function should return an integer result that rounds down the square root.