Problem Statement:
There is an integer array nums sorted in ascending order (with distinct values).
Prior to being passed to your function, nums is possibly rotated at an unknown pivot index k (1 <= k < nums.length) such that the resulting array is [nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]] (0-indexed). For example, [0,1,2,4,5,6,7] might be rotated at pivot index 3 and become [4,5,6,7,0,1,2].
Given the array nums after the possible rotation and an integer target, return the index of target if it is in nums, or -1 if it is not in nums.
You must write an algorithm with O(log n) runtime complexity.
Example 1:
Input: nums = [4,5,6,7,0,1,2], target = 0 Output: 4
Example 2:
Input: nums = [4,5,6,7,0,1,2], target = 3 Output: -1
Example 3:
Input: nums = [1], target = 0 Output: -1
Constraints:
1 <= nums.length <= 5000-10^4 <= nums[i] <= 10^4- All values of
numsare unique. numsis an ascending array that is possibly rotated.-10^4 <= target <= 10^4
Solution:
class Solution {
public int search(int[] nums, int target) {
int start = 0;
int end = nums.length - 1;
while (start <= end) {
int mid = start + (end - start) / 2;
if (nums[mid] == target) {
return mid;
}
// Determine which part is sorted
if (nums[start] <= nums[mid]) {
// Left half is sorted
if (nums[start] <= target && target < nums[mid]) {
end = mid - 1; // Target in the left half
} else {
start = mid + 1; // Target in the right half
}
} else {
// Right half is sorted
if (nums[mid] < target && target <= nums[end]) {
start = mid + 1; // Target in the right half
} else {
end = mid - 1; // Target in the left half
}
}
}
return -1; // Target not found
}
}