lxc自编题题解

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
string s1,s2,s;
string add(string a, string b){
    ll len=max(a.size(), b.size()),jw=0;
    string c="";
    while (a.size()<len) a='0'+a;
    while (b.size()<len) b='0'+b;
    for (ll i=len-1;i>=0;i--){
        ll t1=a[i]-'0',t2=b[i]-'0',t=t1+t2+jw;
        jw=t/10;
        t%=10;
        char ch=t+'0';
        c=ch+c;
    }
    if (jw!=0) return '1'+c;
    return c;
}
int main(){
	cin >> s1 >> s2;
	s=add(s1,s2);
	if (s.size()<=3){
		cout<<s;
		return 0;
	}
	if (s.size()%3==0)
	for (ll i=0;i<s.size();i++){
		cout<<s[i];
		if (i%3==2 && i!=s.size()-1) cout<<',';
	}
	else if (s.size()%3==1){
		cout<<s[0]<<',';
		for (ll i=1;i<s.size();i++){
			cout<<s[i];
			if (i%3==0 && i!=s.size()-1) cout<<',';
		}
	}
	else{
		cout<<s[0]<<s[1]<<',';
		for (ll i=2;i<s.size();i++){
			cout<<s[i];
			if (i%3==1 && i!=s.size()-1) cout<<',';
		}
	}
}

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n,a[1000001],m,cnt;
int main(){
	cin>>n>>m;
	for (ll i=1;i<=n;i++) cin>>a[i];
	sort(a+1,a+n+1);
	for (ll i=1;i<=n;i++){
		ll x=a[i]^m;
		if (x>a[n]) continue;
		ll pos1=lower_bound(a+1,a+n+1,x)-a;
		ll pos2=upper_bound(a+1,a+n+1,x)-a;
		cnt+=pos2-pos1;
		if (x==a[i]) cnt--;
	}
	cout<<cnt/2;
}