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：给定n个数，找出这n个数里丢失的最小的正整数
注意细节：
（1）可能n个数全是负数，输出1
（2）正整数要从1开始记录，数中可能存在重复的数
（3）可能n个数都是连续的正整数，且从1开始，那么输出最大的数+1
代码如下：
#include<bits/stdc++.h>
using namespace std;
int a[1000002];
int main()
{
int n;
while(cin >> n)
{
for(int i = 0;i < n;i ++)
{
cin >> a[i];
}
sort(a,a + n);
int i,fl = 0;
for(i = 0;i < n - 1;i ++)
{
if(a[i] > 0)
{
if(a[i] == 1)
fl = 1;
if(fl)
{
if(a[i] == a[i + 1] || a[i + 1] == a[i] + 1)
continue;
else
{
cout << a[i] + 1 << endl;
break;
}
}
else
{
cout << fl + 1 << endl;
break;
}
}
}
if(i == n - 1)
{
if(a[n - 1] > 0)
cout << a[n - 1] + 1 << endl;
else
cout << 1 << endl;
}
}
return 0;
}