33. Search in Rotated Sorted Array 在旋轉的排序陣列中查詢元素
阿新 • • 發佈:2019-02-14
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.
解題思路:
利用改進的二分查詢搜尋。
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; } };