isqrt function

int isqrt(int n)

Returns the integer square root of n (the floor of its real square root).

Returns 0 for any n less than or equal to zero.

Example:

isqrt(17); // 4
isqrt(16); // 4

Implementation

int isqrt(int n) {
  if (n <= 0) return 0;
  int x = n;
  int y = (x + 1) >> 1;
  while (y < x) {
    x = y;
    y = (x + n ~/ x) >> 1;
  }
  return x;
}