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).
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.
Solution
the core idea is to find the target in already sorted part.
{% codeblock [lang:C++] %}
class Solution {
public:
static int search(vector<int>& nums, int target) {
int first = 0, last = nums.size();
int middle = 0;
while(first != last){
middle = (first+last)/2;
if(target == nums[middle]) return middle;
if(nums[middle]>=nums[first]){
if(target >= nums[first] && target < nums[ middle]) last = middle;
else first = middle+1;
}
else{
if(target >nums[middle] && target <= nums[last-1])
first = middle+1;
else last = middle;
}
}
return -1;
}
};
{% endcodeblock %}
