1144 The Missing Number

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 (≤105). 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

#include 
#include 
using namespace std;
int a[100010];
int n, t;
bool flag;
 
int main() {
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	sort(a, a + n);
	t = 1;
	for (int i = 0; i < n; i++) {
		if (a[i] > 0) {
			flag = 1;
		}
		if (flag) {
			if (t < a[i]) {
				cout << t;
				return 0;
			} else if (t == a[i]) {
				t++;
			}
		}
	}
	cout << t;
	return 0;
}