【二分查找】面试题53 - II. 0～n-1中缺失的数字

 1 class Solution {
 2 public:
 3     int missingNumber(vector<int>& nums) 
 4     {
 5         int i = 0;
 6         int j = nums.size() - 1;
 7 
 8         while(i <= j) 
 9         {
10             int m = (i + j) / 2;
11 
12             if(nums[m] == m) 
13             {
14                 i = m + 1;
15             }
16             else 
17             {
18                 j = m - 1;
19             }
20         }
21         return i;
22     }
23 };

 1 class Solution {
 2 public:
 3     int missingNumber(vector<int>& nums) 
 4     {
 5         int n = nums.size();
 6         int res = 0;
 7         for(int i = 0;i < n;i++) 
 8         {
 9             res ^= (nums[i] ^ i);
10         }
11         
12         return res ^ n;
13     }
14 };