版权声明: https://blog.csdn.net/ysq96/article/details/81747762
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:
题目几个关键词:①正整数②未出现的③范围是int
有了限定,就会好做一点。首先利用map将数字映射到这个数字出现的次数,只要出现过,这个数字必定大于0。再利用一个num从1依次递增开始判断map中对应出现次数是否大于0,否则就是未出现过的
C++:
#include "iostream"
#include "map"
using namespace std;
map<int,int> e;
int main(){
int n;
cin>>n;
for (int i=0;i<n;i++)
{
int temp;
cin>>temp;
e[temp]++;
}
int num=1;
while (e[num]>0)num++;
cout<<num<<endl;
return 0;
}