Valid Perfect Square
Given a positive integer num, write a function which returns True if num is a perfect square else False.
Note: Do not use any built-in library function such as sqrt.
Example 1:
Input: 16
Returns: True
Example 2:
Input: 14
Returns: False
public class Solution {
public boolean isPerfectSquare(int num) {
long low = 0, high = num;
while (low + 1 < high) {
long middle = low + (high - low) / 2;
if (middle * middle == num) {
return true;
} else if (middle * middle > num) {
high = middle;
} else {
low = middle;
}
}
if (high * high == num) {
return true;
}
if (low * low == num) {
return true;
}
return false;
}
}
Hope this helps,
Michael