FindRotatedArrMin.java

/**
 * 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.
 * 
 * Tags: Array, Binary Search
 */
class FindRotatedArrMin {
    public static void main(String[] args) {
        int[] num = { 3, 4, 5, 6, 0, 1, 2 };
        // int[] num = { 4, 5, 6, 7, 0, 1, 2 };
        System.out.println(findMin(num));
    }
    
    static int findMin(int[] num) {
        int l = 0;
        int r = num.length - 1;
        if (num.length == 1 || num[l] < num[r]) return num[0];
        
        int mid = 0;
        while (l < r) {
            mid = l + (r - l) / 2;
            System.out.println(mid);
            if (num[l] < num[mid]) l = mid;
            else r = mid;
        }
        return num[l + 1];
    }
    
}