On Tue, Sep 8, 2009 at 2:09 AM, ayush chauhan <therajput.ay...@gmail.com>wrote:
> Cud u plz explain the logic behind this?
On Mon, Sep 7, 2009 at 9:44 PM, Gokul <spgo...@gmail.com> wrote:
>
> you can try this......
> int add(int x, int y)
> {
> if (!x) return y;
> else
> return add((x & y) << 1, x ^ y);
> }
>
Lets consider you want to add 34590 and 987387065 in decimal notation.
9 8 7 6 8 7 0 6 5
+ 3 4 5 5 9 0
---------------------------
9 8 7 9 2 2 5 5 5 ----> addition of digits neglecting carry
+ 0 0 0 1 1 0 1 0 0 ---> represents carry
--------------------------
9 8 7 0 3 2 6 5 5
+ 0 0 1 0 0 0 0 0 0
---------------------------
9 8 8 0 3 2 6 5 5
+ 0 0 0 0 0 0 0 0 0
So ans is 988032655.
Similarly, In terms of bit representation, for addition of two numbers 'x'
and 'y', (x&y)<<1 represents the carry number and x^y represents the number
neglecting the carry. So for example let the number is 43 & 14.
x = 43 = 1 0 1 0 1 1
y = 14 = 0 0 1 1 1 0
1 0 1 0 1 1
+ 0 0 1 1 1 0
------------------
1 0 0 1 0 1 ---> x^y
+ 0 1 0 1 0 0 ---> (x&y)<<1
------------------
1 1 0 0 0 1
+ 0 0 1 0 0 0
------------------
1 1 1 0 0 1
+ 0 0 0 0 0 0
------------------
hence 43 + 14 = 111001 = 57
--
Shishir Mittal
Ph: +91 9936 180 121
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