SortedAndRotatedArraySearch.java

package com.interview.binarysearch;

/**
 * @author Tushar Roy
 * Date 01/22/17
 *
 * Search in sorted and rotated array. In one version duplicate is not allowed and
 * in another version duplicate is allowed.
 *
 * Time complexity with no duplicate - O(logn)
 * Time complexity with duplicates - O(n)
 *
 * https://leetcode.com/problems/search-in-rotated-sorted-array/
 * https://leetcode.com/problems/search-in-rotated-sorted-array-ii/
 */
public class SortedAndRotatedArraySearch {

    /**
     * Duplicates are not allowed in arr.
     */
    public int search(int arr[],int search){
        int low =0;
        int high = arr.length-1;
        while(low <= high){
            int mid = (low + high)/2;
            if(arr[mid] == search){
                return mid;
            }
            
            if(arr[mid] < arr[high]){
                if(arr[mid] < search && search <= arr[high]){
                    low = mid+1;
                }else{
                    high = mid-1;
                }
            }else{
                if(search >= arr[low] && search < arr[mid]){
                    high = mid-1;
                }else{
                    low = mid+1;
                }
            }
        }
        return -1;
    }

    /**
     * Duplicates are allowed in arr.
     */
    public boolean searchWithDuplicates(int[] arr, int search) {
        int low =0;
        int high = arr.length-1;
        while(low <= high){
            int mid = (low + high)/2;
            if(arr[mid] == search) {
                return true;
            }
            //if low is same as mid then increment low.
            if (arr[mid] == arr[low]) {
                low++;
            } else if (arr[mid] == arr[high]) { //if high is same as mid then decrement high.
                high--;
            } else if (arr[mid] < arr[high]) {
                if(arr[mid] < search && search <= arr[high]) {
                    low = mid + 1;
                } else {
                    high = mid - 1;
                }
            } else {
                if(search >= arr[low] && search < arr[mid]) {
                    high = mid - 1;
                } else {
                    low = mid + 1;
                }
            }
        }
        return false;
    }
    
    public static void main(String args[]){
        SortedAndRotatedArraySearch ras = new SortedAndRotatedArraySearch();
        int arr1[] = {1,2,5,6,7,8,11,21};
        System.out.print(ras.search(arr1, 1));
        System.out.print(ras.search(arr1, 5));
        System.out.print(ras.search(arr1, 22));
        System.out.println();
    
        int arr2[] = {18,21,1,2,5,6,7,8,10,15};
        System.out.print(ras.search(arr2, 1));
        System.out.print(ras.search(arr2, 5));
        System.out.print(ras.search(arr2, 10));
        System.out.print(ras.search(arr2, 14));
        System.out.println();

        int arr3[] = {7,8,15,17,18,21,1,2,5,6};
        System.out.print(ras.search(arr3, 1));
        System.out.print(ras.search(arr3, 5));
        System.out.print(ras.search(arr3, 10));
        System.out.print(ras.search(arr3, 7));
        System.out.print(ras.search(arr3, 6));
        System.out.print(ras.search(arr3, 16));
    }
}