Is cube root integer?

Question

This seems to be simple but I cannot find a way to do it. I need to show whether the cube root of an integer is integer or not. I used is_integer() float method

Answer 1

To elaborate on the answer by @nneonneo, one could write a more general kth-root function to use instead of cube_root,

def kth_root(n,k):
    lb,ub = 0,n #lower bound, upper bound
    while lb < ub:
        guess = (lb+ub)//2
        if pow(guess,k) < n: lb = guess+1
        else: ub = guess
    return lb

def is_perfect_cube(n):
    return kth_root(n,3) == n