Hdu 2709 Sumsets

Question:

Divide n into the sum of several numbers, which is a positive integer equal to 2 ^ x.

Code:
 
# Include <stdio. h>
_ Int64 I, a [1000001] = {, 2 };
Int main ()
{
For (I = 3; I <1000001; I ++)
{
If (I & 1) = 1)
{
A [I] = a [I-1]; // I is an odd number the same as the previous one
}
Else
{
A [I] = (a [I-2] + a [I> 1]) % 1000000000; // contains 1: a [I-1] fill in 11 for each case, not including 1: a [I/2] each case * 2
}
}
While (scanf ("% I64d", & I )! = EOF)
{
Printf ("% I64d \ n", a [I]);
}
Return 0;
}