Search in Rotated Sorted Array

Desicription

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.

Solution

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class Solution {
public:
int search(vector<int>& nums, int target) {
int left = 0;
int right = nums.size()-1;
while(left <= right){
int mid = (left + right) >> 1;
if(nums[mid] == target)
return mid;
if(nums[mid] < nums[right]){
if(nums[mid] < target && nums[right] >= target)
left = mid + 1;
else
right = mid - 1;
}
else{
if(nums[mid] > target && nums[left] <= target)
right = mid - 1;
else
left = mid + 1;
}
}
return -1;
}
};