33. Search in Rotated Sorted Array

33. Search in Rotated Sorted Array

Suppose an array sorted in ascending order 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).

You are given a target value to search. If found in the array return its index, otherwise return -1.

You may assume no duplicate exists in the array.

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number}
 */
var search = function(A, target) {
    //有序数组查找固定值，第一反应就是二分。 
    var lo = 0;
    var hi = A.length - 1;
    
    while (lo < hi) {
        var mid = Math.floor((lo + hi) / 2);
        if (A[mid] == target) return mid;
        
        if (A[lo] <= A[mid]) {
            if (target >= A[lo] && target < A[mid]) {
                hi = mid - 1;
            } else {
                lo = mid + 1;
            }
        } else {
            if (target > A[mid] && target <= A[hi]) {
                lo = mid + 1;
            } else {
                hi = mid - 1;
            }
        }
    }
    return A[lo] == target ? lo : -1;
};