Modified 2-color sort

Given an array of integers containing only 0s and 1s.You have to place all the 0s in even position and 1s in odd position. And if suppose, no. of 0s exceed no. of 1s or vice versa then keep the exceeding integers untouched. Do that in ONE PASS and without taking extra memory (modify the array in-place).

For Example :
Input Array:    [0,1,1,0,1,0,1,0,1,1,1,0,0,1,0,1,1]

Output Array: [0,1,0,1,0,1,0,1,0,1,0,1,0,1,1,1,1]

Solution :

Find the wrong positions for 0 and 1 and swap them

Complexity :

• Time : O(N)
• Space : O(1)

Code :

void interleave_0_1(int input[], int N){

int i=0, j=1;

while(1){

while(i < N && input[i] == 0)

i += 2;

while(j < N && input[j] == 1)

j += 2;

if(i < N && j < N){

input[i] ^= input[j];
input[j] ^= input[i];
input[i] ^= input[j];

}
else

break;

}

}