pat 1144

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：这题送20分

代码如下

#include<cstdio>
#include<unordered_map>
using namespace std;
int main(){
    int n;
    int temp;
    unordered_map<int,bool> m;
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        scanf("%d",&temp);
        m[temp]=true;
    }
    int i=1;
    while(true){
        if(m.count(i)==0){
            printf("%d",i);
            break;
        }
        i++;
    }
    return 0;
}