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Tested Python solution for LeetCode 279 with 17 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 279 # by problem number
lcpy gen -s perfect_squares # by problem name
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, and 16 are perfect squares while 3 and 11 are not.
Input: n = 12
Output: 3
Explanation: 12 = 4 + 4 + 4.
Input: n = 13
Output: 2
Explanation: 13 = 4 + 9.
class Solution:
# Time: O(n * sqrt(n))
# Space: O(n)
def num_squares(self, n: int) -> int:
dp = [0] + [n + 1] * n
for i in range(1, n + 1):
j = 1
while j * j <= i:
dp[i] = min(dp[i], dp[i - j * j] + 1)
j += 1
return dp[n]
| Time | Space |
|---|---|
| O(n * sqrt(n)) | O(n) |