题目
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.
分析
老题了，就不多写了，二分+注意边界条件，如果不确定边界条件把所有的情况都列出来，再将相同处理的情况进行融合。
代码
public int search(int[] nums, int target) {
if(nums == null || nums.length == 0) return -1;
int left = 0, right = nums.length - 1;
while(left < right){
int mid = left + (right - left) / 2;
if(nums[mid] == target){
return mid;
}
if(nums[mid] >= nums[left]){ //左侧有序
if(nums[mid] > target && nums[left] <= target){
right = mid - 1;
}else{
left = mid + 1;
}
}else{ //右侧有序
if(nums[mid] <= target && nums[right] >= target){
left = mid + 1;
}else{
right = mid - 1;
}
}
}
return nums[left] == target ? left : -1;
}