leetcode 033 Search in Rotated Sorted Array

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.

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class Solution {
public:
int search(vector<int>& nums, int target) {
int len = nums.size();

if(len==0) return -1;

int pivot=0;

for(int i=1; i<len; i++) {
if(nums[i] < nums[i-1]) {
pivot=i;
break;
}
}

int left = 0, end = 0;

if(target < nums[pivot]) return -1;
if(pivot-1>=0 && target > nums[pivot-1]) return -1;

if(pivot-1>=0 && target >= nums[0] && target <= nums[pivot-1]) {
left = 0;
end = pivot-1;
} else {
left = pivot;
end = len-1;
}

while(left <= end) {
int mid = (left+end)/2;
if(target==nums[mid]) return mid;
else if(target > nums[mid]) {
left = mid+1;
} else {
end = mid-1;
}
}

return -1;
}
};