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