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

 

#include <map>
#include <set>
#include <queue>
#include <cmath>
#include <stack>
#include <vector>
#include <string>
#include <cstdio>
#include <cstring>
#include <climits>
#include <iostream>
#include <algorithm>
#define wzf ((1 + sqrt(5.0)) / 2.0)
#define INF 0x3f3f3f3f
#define LL long long
using namespace std;

const int MAXN = 1e6 + 10;

int n, A[MAXN] = {0}, a;

int main()
{
    scanf("%d", &n);
    for (int i = 0; i < n; ++ i)
    {
        scanf("%d", &a);
        if (a <= 0 || a > MAXN) continue;
        A[a] = 1;
    }
    for (int i = 1; ; ++ i)
        if (A[i] == 0)
        {
            printf("%d\n", i);
            break;
        }
    return 0;
}