[PAT] 1144 The Missing Number（20 分）

1144 The Missing Number（20 分）

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 (≤10​5​​). 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

题意：给出n个数，输出不在给出的数中的最小正整数。
分析：1.用set去接收这些数（排序+去重）
题解：

 #include<cstdlib>
 #include<cstdio>
 #include<set>
 using namespace std;
 int main() {
     int n;
     set<int> s;
     scanf("%d", &n);
     ; i != n; i++) {
         int t;
         scanf("%d", &t);
         s.insert(t);
     }
     int pre = *(s.begin());
     for (set<int>::iterator it = ++s.begin(); it != s.end(); it++) {
          && pre+ > ) {
             printf();
             ;
         }
         pre = *(it);
     }
     //如果遍历到最后一个仍然找不到符合要求的结果，
     //则输出最大的数之后的正整数（最大的数可能为正，或者仍为负）
     ) {
         printf();
     }
     else {
         printf();
     }
     ;
 }