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Odd-Even Sort

Idea​

  • compare all (odd,even) indexed pairs of adjacent elements
  • if a pair is in the wrong order, switch elements
  • then alternate between (odd,even) and (even,odd) pairs

Implementation​

public class OddEvenSort{
    public static void sort(int[] arr){
        if(arr==null || arr.length<=1){
            return;
        }
        boolean sorted = false;
        int len = arr.length;
        while(!sorted){
            sorted = true;
            //(odd,even) pairs
            for(int i=1; i<len-1; i+=2){
                if(arr[i] > arr[i+1]){
                    swap(arr,i,i+1);
                    sorted = false;
                } 
            }
            //(even,odd) pairs
            for(int i=0; i<len-1; i+=2){
                if(arr[i] > arr[i+1]){
                    swap(arr,i,i+1);
                    sorted = false;
                }
            }
        }
    }

    public static void swap(int[] arr, int i, int j){
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }
}

Runtime​

  • Time O(n^2)
  • Space O(1)

Reference​