# 279. Perfect Squares """ given an integer 'n', return the least number of perfect square numbers that sum to 'n'. a perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself. for example, 1,4,9,16 are perfect squares while 3 and 11 are not. """ class Solution(object): def numSquares(self, n): """ :type n: int :rtype: int """ if n < 2: return n lst = [] i = 1 while i * i <= n: lst.append(i * i) i += 1 cnt = 0 to_check = {n} while to_check: cnt += 1 tmp = set() for x in to_check: for y in lst: if x == y: return cnt if x < y: break tmp.add(x - y) to_check = tmp return cnt if __name__ == "__main__": obj = Solution() print(obj.numSquares(12)) print(obj.numSquares(13))