<aside> 💡 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
</aside>
class Solution {
public int numSquares(int n) {
int[] dp = new int[n+1];
Arrays.fill(dp, n+1);
dp[0] = 0;
dp[1] = 1;
for (int j = 2; j <=n; j++) {
for (int i = 1; i*i<=j; i++){
dp[j] = Math.min( dp[j-i*i]+1, dp[j]);
}
}
return dp[n];
}
}