标签：appear ++ div ref art mic empty front integer
題目
Given a non-empty array of integers, every element appears twice except for one. Find that single one.
Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
Example 1:
Input: [2,2,1] Output: 1
Example 2:
Input: [4,1,2,1,2] Output: 4
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我的思考是這樣，先排序然後兩個兩個一組尋找(因為題目是只有一個數出現一次，其它都出現兩次)
排序的部分是參考 QuickSort
1 public class Solution { 2 public int SingleNumber(int[] nums) { 3 QuickSort(ref nums, 0, nums.Length -1); 4 5 if (nums.Length == 1) return nums[0]; 6 7 for(int i = 0; (i + 2) < nums.Length; i += 2) 8 { 9 if (nums[i] != nums[(i + 1)]) return nums[i]; 10 } 11 12 return nums[nums.Length - 1]; 13 } 14 void Swap(ref int[] arr,int a, int b) 15 { 16 int temp = arr[a]; 17 arr[a] = arr[b]; 18 arr[b] = temp; 19 } 20 21 int Partition(ref int[] arr,int front,int end) 22 { 23 int i = front - 1; 24 int j = front; 25 int pivot = arr[end]; 26 27 for(;j < end; j++) 28 { 29 if(pivot> arr[j]) 30 { 31 i++; 32 Swap(ref arr,i,j); 33 } 34 } 35 i++; 36 Swap(ref arr, i, end); 37 return i; 38 39 } 40 41 void QuickSort(ref int[] arr,int front,int end) 42 { 43 if(front < end) 44 { 45 int middle = Partition(ref arr, front, end); 46 QuickSort(ref arr, front, middle - 1); 47 QuickSort(ref arr, middle + 1, end); 48 } 49 50 } 51 }
有過，不過這速度真慘
改用MS內建的sort
public class Solution { public int SingleNumber(int[] nums) { //QuickSort(nums, 0, nums.Length -1); Array.Sort(nums); if (nums.Length == 1) return nums[0]; for(int i = 0; (i + 2) < nums.Length; i += 2) { if (nums[i] != nums[(i + 1)]) return nums[i]; } return nums[nums.Length - 1]; } }
有700ms的差距 QQ
标签：appear ++ div ref art mic empty front integer
原文地址：https://www.cnblogs.com/seako/p/10493605.html
