Giới thiệu
include <iostream>
include <type_traits>
using namespace std;
void quicksort(int left, int right,int array[]);
int main()
{
int n;
int array[100000];
cin >> n;
n=n-1;
for (int i = 0; i < n; i++)
cin >> array[i];
quicksort(0, n,array);
for (int i = 0; i < n; i++)
{
if (array[i]+1!=array[i+1])
{
cout << array[i]+1;
}
}
}
void quicksort(int left, int right,int array[])
{
int x = array[(left + right) / 2];
int i = left;
int j = right;
while (i <= j)
{
while (array[i] < x)
i = i + 1;
while (array[j] > x)
j = j - 1;
if (i <= j)
{
int temp = array[i];
array[i] = array[j];
array[j] = temp;
i = i + 1;
j = j - 1;
}
}
if (left < j)
quicksort(left, j,array);
if (i < right)
quicksort(i, right,array);
}