Given an integer 'target', return the least number of perfect square numbers that sum to n.

perfect_squares.py

from math import sqrt
def numSquares(target):
    squares = [n ** 2 for n in range(1, int(sqrt(target)) + 1)]
    level = 0
    remainders = {target}
    while True:
        level += 1
        next_remainders = set()
        for remainder in remainders:
            for square in squares:
                if square == remainder:
                    return level
                if square > remainder:
                    break
                next_remainders.add(remainder - square)
        remainders = next_remainders