HDU 5014Number Sequence

#include <cstdlib>
#include <cctype>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>
#include <string>
#include <iostream>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <stack>
using namespace std;
typedef long long ll;

int n;
int num(int x)
{
    int k=0;
    while (x)
    {
        k++;
        x/=2;
    }
    return k;
}

int b[100003];
int a[100003];
int main()
{
    int n;
    while (scanf("%d",&n)!=EOF)
    {
        memset(b,0,sizeof(b));
        for (int i=n;i>=0;i--)
        if (!b[i]){
        int k=((1<<num(i))-1)^i;
        b[i]=k;
        b[k]=i;
        }
        
        printf("%I64d\n",(ll)(n+1)*n);
        for (int i=0;i<=n;i++) scanf("%d",&a[i]);
        for (int i=0;i<n;i++) printf("%d ",b[a[i]]);
        printf("%d\n",b[a[n]]);
    }
    return 0;
}