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# Perfect Squares

Given a positive integer n, find the least number of perfect square numbers (for example, `1, 4, 9, 16, ...`) which sum to n.

**Example 1:**

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

**Example 2:**

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

```java
class Solution {
    public int numSquares(int n) {
        int dp[] = new int[n + 1];
        dp[1] = 1;
        for (int i = 2; i <= n; i++) {
            dp[i] = i;
            for (int j = 1; j * j <= i; j++) {
                dp[i] = Math.min(dp[i], dp[i - j * j] + 1);
            }
        }
        return dp[n];
    }
}
```