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 (≤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

浅析

送分题

Code

#include 
#include 
using namespace std;
int main() {
    int n, a, num = 0;
    cin >> n;
    map<int, int> m;
    for (int i = 0; i < n; i++) {
        cin >> a;
        m[a]++;
    }
    while(++num)
        if (m[num] == 0) break;
    cout << num;
    return 0;
}