222

int main()
{
int arr[] = {4,2,3,5,6};
int n = sizeof(arr) / sizeof(int);
int t = 0;
for (int i = 1; i <= n+1; i++)
{
t ^= i;
}

for (int i = 0; i < n; i++)
{
t ^= arr[i];
}

cout << t << endl;

int buf[] = { 1, 0, 2, 0, 5, 5, 8 };
int size = sizeof(buf)/sizeof(int);

int l = 0;
int r = size - 1;
while (r != l)
{
if (buf[r] != 0 && buf[l]==0)
{
int tmp = buf[r];
buf[r] = buf[l];
buf[l] = tmp;
l++;
r--;
continue;
}

if (buf[r] == 0)
{
r--;
}

if (buf[l] != 0)
{
l++;
}
}

return 0;
}