PAT甲级——A1144 TheMissingNumber【20】

Given N integers, you are supposed to find the smallest positive integer that is NOT in the given list.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N ( $\leq). Then N integers are given in the next line, separated by spaces. All the numbers are in the range of int.$

Output Specification:

Print in a line the smallest positive integer that is missing from the input list.

Sample Input:

10
5 -25 9 6 1 3 4 2 5 17

Sample Output:

7

Solution:

　　水题，没得意思

　　两种方法，用map存储后查找即可

　　另一种方法就是排序后从1查找即可

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 using namespace std;
 5 int main()
 6 {
 7     int n, x, res = 1;
 8     vector<int>v;
 9     cin >> n;
10     while (n--)
11     {
12         cin >> x;
13         if (x > 0)
14             v.push_back(x);
15     }
16     sort(v.begin(), v.end());
17     for (auto a : v)
18         if (a == res)
19             res++;
20     cout << res;
21     return 0;
22 }