1144 The Missing Number （20 分）

思念在延续

于 2019-01-16 09:47:21 发布

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分类专栏： PAT集训

本文链接：https://blog.youkuaiyun.com/huantonglei/article/details/86502462

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本文介绍了一种算法，用于从给定的整数列表中找出最小的未出现的正整数。通过使用C++的map数据结构，该算法能够有效地遍历列表并找到缺失的数字。

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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:

分析：找出最小的不连续正整数

代码如下：

#include <bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    map<int,int> m;
    for (int i=0;i<n;i++)
    {
        int x;
        cin>>x;
        m[x]++;
    }
    int num=1;
    while (m[num]>0)
        num++;
        cout<<num<<endl;
    return 0;
}