Monday, March 2, 2015

Find Minimum in Rotated Sorted Array II


Follow up for "Find Minimum in Rotated Sorted Array":
What if duplicates are allowed?
Would this affect the run-time complexity? How and why?
Suppose a sorted array is rotated at some pivot unknown to you beforehand.
(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).
Find the minimum element.
The array may contain duplicates.
Note: binary search
Run time complexity is O(logn), space complexity is constant space.
public class Solution {
    public int findMin(int[] num) {
        int L = 0, R = num.length - 1;
        
        while(L < R && num[L] >= num[R]) { //when num[L] < num[R], num[L] is the minimum number, just return num[L]
            int mid = (L + R) / 2;
            if(num[mid] > num[R]) {
                L = mid + 1;
            }else if(num[mid] < num[L]) {
                R = mid;
            }else {          //num[L] == num[mid] == num[R]
                L = L + 1;
            }
        }
        return num[L];
    }
}

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