```
//f(n) = f(n-3) * 3 when n >= 7
public int integerBreak(int n) {
int [] ans = {0, 0, 1, 2, 4, 6, 9};
if (n <= 6) return ans[n];
int f1 = 4, f2 = 6, f3 = 9;
for (int i = 7; i <= n; i++) {
int tmp = f3;
f3 = f1*3;
f1 = f2;
f2 = tmp;
}
return f3;
}
```