279. Perfect Squares
Question
Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n.
For example, given n = 12, return 3 because 12 = 4 + 4 + 4; given n = 13, return 2 because 13 = 4 + 9.
Quick Hints
- Dynamic Programming
sol[i] = Math.min(sol[i], sol[i - j * j] + 1)
Solution
Time complexity
O (n ^ 2)
Space complexity
O(n)