Given a array of size 'n' with 0's and 1's as its elements, sort the array in ascending order

Its cool problem.

Method 1)

Count the number of 1's (ones) in the array , say k.
Then simply set last k elements to 1 and n-k elements to 0(zero).
(other way is count 0's)


Its takes total (n+ n = 2n) = O(N) time.


Method 2)

f = 0;
l = n -1;
for ( ; f < l; ) {
if(arr[f]) {
if(!arr[l]) {
arr[f++]=0;
arr[l]=1;
}
l--;
} else {
arr[l] && l--;
f++;
}
}




Let me know which is better ?? And if there is any better approach..