Find Minimum in Rotated Sorted Array

Suppose a sorted array 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).

Find the minimum element.

You may assume no duplicate exists in the array.

 

ERROR: control may reach end of non-void function

No return type after "if"..

 1 class Solution {
 2 public:
 3     int findMin(vector<int>& nums) {
 4         if(nums.empty()) return 0;
 5         
 6         return helper(nums, 0, nums.size() - 1);
 7     }
 8     
 9     int helper(vector<int>& nums, int left, int right){
10         if(left == right) return nums[left];
11         if(right - left == 1) return min(nums[left], nums[right]);
12         
13         int mid = left + (right - left) / 2;
14             
15         if(nums[left] < nums[right]) //didn't rotate
16             return nums[left];
17         if(nums[mid] > nums[left])
18             return helper(nums, mid, right);
19         if(nums[mid] < nums[left])
20             return helper(nums, left, mid);
21     }
22 };
23 
24
View Code

 

Runtime: 4ms

 1 class Solution {
 2 public:
 3     int findMin(vector<int>& nums) {
 4         if(nums.empty()) return 0;
 5         
 6         return helper(nums, 0, nums.size() - 1);
 7     }
 8     
 9     int helper(vector<int>& nums, int left, int right){
10         if(left == right) return nums[left];
11         if((right - left) == 1) return min(nums[left], nums[right]);
12         
13         int mid = left + (right - left) / 2;
14             
15         if(nums[left] < nums[right]) //didn't rotate
16             return nums[left];
17         else if(nums[mid] > nums[left])
18             return helper(nums, mid, right);
19         else
20             return helper(nums, left, mid);
21     }
22 };
23 
24

 

posted @ 2015-10-12 09:38  amazingzoe  阅读(106)  评论(0)    收藏  举报