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, and 16 are perfect squares while 3 and 11 are not.

Example 1:

Input: n = 12
Output: 3
Explanation: 12 = 4 + 4 + 4.

Example 2:

Input: n = 13
Output: 2
Explanation: 13 = 4 + 9.

Constraints:

• 1 <= n <= 104

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class Solution:
    def numSquares(self, n: int) -> int:
        dp = [math.inf] * (n + 1)
        dp[0] = 0
        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]