与运算
0&n=0

1&奇数=1

1&偶数=0

#include <bits/stdc++.h>
//dfs 大法师
#define ll long long
using namespace std;
const int mod=20100403;
const int Inf=0x3f3f3f3f;
inline int read()
{
	int x=0,f=1;char ch=getchar();
	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}
	while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
	return x*f;
}

int m1[]={0,31,28,31,30,31,30,31,31,30,31,30,31};
int m2[]={0,31,29,31,30,31,30,31,31,30,31,30,31};
void Get_Time()
{
    time_t timep;

    time(&timep); //获取从1970至今过了多少秒，存入time_t类型的timep
    printf("%s", ctime(&timep));//用ctime将秒数转化成字符串格式，输出：Thu Feb 28 14:14:17 2019
}
void solve()
{
    int t;
    cin>>t;
    while(t--)
    {
        ll n,k;
        cin>>n>>k;
        if(n==4&&k==3){cout<<-1<<endl;continue;}
        ll d=n-1-k;
        if(k==n-1)
        {
            cout<<k<<" "<<k-1<<endl;
            cout<<0<<" "<<n-1-3<<endl;
            cout<<1<<" "<<3<<endl;
            for(int a=0;a<n/2;a++)
            {
                if(a!=0&&a!=1&&a!=n-k&&a!=3)cout<<a<<" "<<n-1-a<<endl;
            }
        }
        else
        if(k!=0){
                cout<<0<<" "<<d<<endl;
                cout<<k<<" "<<n-1<<endl;
                for(int a=0;a<n/2;a++)
                {
                    if(a!=0&&a!=k&&a!=n-1-k)cout<<a<<" "<<n-1-a<<endl;
                }
        }
        else
        {
            for(int a=0;a<n/2;a++)
                cout<<a<<" "<<n-1-a<<endl;
        }
        

    }
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    solve();
    return 0;
}

或运算

#include<bits/stdc++.h>
using namespace std;
int n;
int main(){
	int t;cin>>t;
	while(t--){
		int a,b;cin>>a>>b;
		int ans=b-a;
		if((b|a)==b)
		{
			puts("1");continue;
		}
		for(int i=1;i+1<=ans;i++)
		{
			if(((a+i)|b)==b||((b+i)|a)==b+i) ans=i+1;
		}
		cout<<ans<<endl;
	}
}