279. 完全平方数

279. 完全平方数

class Solution {
    public int numSquares(int n) {
        int[] dp = new int[n + 1];
        Arrays.fill(dp, Integer.MAX_VALUE);
        dp[0] = 0;
        int maxSquareLen = (int)Math.sqrt(n) + 1;
        int[] squareNum = new int[maxSquareLen];
        for (int i = 0; i < maxSquareLen; i++) {
            squareNum[i] = i * i;
        }
        for (int i = 1; i <= n; i++) {
            for (int index = 1; index < maxSquareLen; index++) {
                if (i < squareNum[index]) {
                    break;
                }
                dp[i] = Math.min(dp[i], dp[i - squareNum[index]] + 1);
            }
        }
        return dp[n];
    }
}