[中等]寻找缺失的数

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 using namespace std;
 5 
 6 //方法1
 7 class Solution {
 8 public:
 9     /**    
10      * @param nums: a vector of integers
11      * @return: an integer
12      */
13     int findMissing(vector<int> &nums) {
14         // write your code here
15         int n=nums.size()+1;
16         int sum=(n-1)*n/2;
17         for(int i=0;i<nums.size();i++)
18             sum-=nums[i];
19         return sum;
20     }
21 };
22 
23 //方法2
24 class Solution {
25 public:
26     /**    
27      * @param nums: a vector of integers
28      * @return: an integer
29      */
30     int findMissing(vector<int> &nums) {
31         // write your code here
32         sort(nums.begin(),nums.end());
33         for(long i=0;i<nums.size();i++)
34         {
35             if(nums[i]!=i)
36                 return i;
37         }
38         return nums.size();
39     }
40 };
41 
42 int main () 
43 {
44     int a[5]={0,1,2,3,5};
45     vector<int> v(a,a+5);
46     Solution s;
47     cout<<s.findMissing(v);
48 }