PAT 1144. The Missing Number (20) – 甲级

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

题目大意：给n个数字，找到不在这个数字列表里面的最小的正整数
分析：将每个数字出现的次数存储在map里面，num从1开始，如果m[num] == 0说明不存在，则输出这个num～

#include <iostream>
#include <map>
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;
}

#include <iostream>

#include <map>

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;

}

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