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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.
解题思路:
利用改进的二分查找搜索。
class Solution {
public:
int search(vector<int>& nums, int target) {
int begin = 0;
int end = nums.size() - 1;
while(begin <= end)
{
int mid = (begin + end) / 2;
cout << mid << " " << target << endl;
if(nums[mid] == target)
return mid;
else if(nums[mid] < target)
{
if(nums[mid] >= nums[begin]) (5)
begin = mid + 1;
else if(nums[mid] < nums[begin])
{
if(target >= nums[begin]) (3)
end = mid - 1;
else if(target < nums[begin]) (1)
begin = mid + 1;
}
else
end = mid - 1;
}
else if(nums[mid] > target)
{
if(nums[mid] > nums[begin])
{
if(target >= nums[begin]) (4)
end = mid - 1;
else if(target < nums[begin]) (6)
begin = mid + 1;
}
else if(nums[mid] < nums[begin]) (2)
end = mid - 1;
else
begin = mid + 1;
}
}
return -1;
}
};