279. Perfect Squares

Medium
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 <= 10^4

解題

func numSquares(n int) int {
dp := make([]int, n + 1)
dp[0] = 0
dp[1] = 1
​
for i := 2; i <= n; i++ {
dp[i] = math.MaxInt32
for j := 1; i - j * j >= 0; j++ {
dp[i] = min(dp[i], dp[i - j * j] + 1)
}
}
​
return dp[n]
}
​
func min(a, b int) int {
if a < b { return a }
return b
}