Find Minimum in Rotated Sorted Array

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.

You may assume no duplicate exists in the array.

public class Solution {
    public int findMin(int[] num) {
        if(num == null || num.length == 0) return 0;
        int str = 0, end = num.length - 1;
        while(str < end){
            int mid = (str + end) / 2;
            if(num[mid] < num[end]){
                end = mid;
            }else{
                str = mid + 1;
            }
        }
        return num[str];
    }
}