Search in Rotated Sorted Array II
Follow up for Search in Rotated Sorted Array:
What if duplicates are allowed?
Would this affect the run-time complexity? How and why?
Write a function to determine if a given target is in the array.
Example:
Given [1, 1, 0, 1, 1, 1] and target = 0, return true.
Given [1, 1, 1, 1, 1, 1] and target = 0, return false.
Solution:
Similar to Find Minimum in Rotated Sorted Array II. If we found duplicate, we need to move start or end. In ideal case, we should set start = mid or end = mid. However, since the array is rotated, the duplicate numbers could be appeared in both side of the array, for exemple: [4,4,5,6,7,0,1,2,4,4]. Therefore, we can only move start or end by one step at a time. For instance: if nums[mid] == nums[start], start++. If nums[mid] == nums[end], end--.
Code:
public boolean search(int[] nums, int target) {
if (nums == null || nums.length == 0) {
return false;
}
int start = 0;
int end = nums.length - 1;
while (start + 1 < end) {
int mid = start + (end - start) / 2;
if (nums[start] == nums[mid]) {
start++;
} else if (nums[end] == nums[mid]) {
end--;
} else if (nums[start] <= nums[mid]) {
if (nums[start] <= target && target <= nums[mid]) {
end = mid;
} else {
start = mid;
}
} else {
if (nums[mid] <= target && target <= nums[end]) {
start = mid;
} else {
end = mid;
}
}
}
return nums[start] == target || nums[end] == target;
}