在转动过得有序数组中寻找目标值

public int search (int[] A, int target) {
        if(A==null) return -1;
        int left = 0;
        int right = A.length-1;
        //不存在重复
        while (left<=right){
            int mid = (right-left)/2+left;
            if (A[mid]==target) return mid;
            else if(A[mid]<A[right]){
                if (target>A[mid] && target<=A[right]){
                    left = mid+1;
                }else {
                    right= mid-1;
                }
            }else {
                if(target>=A[left] && target<A[mid]){
                    right = mid-1;
                }else {
                    left = mid+1;
                }
            }
        }
        return -1;
    }