Submission #930515

#	Time	Username	Problem	Language	Result	Execution time	Memory
930515		Baizho	XOR Sum (info1cup17_xorsum)	C++14	45 / 100	1618 ms	15964 KiB

xorsum

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
  
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
 
// #pragma GCC optimize("Ofast,unroll-loops,fast-math")
// #pragma GCC target("popcnt")
 
 
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll,ll> pll;
 
#define sz size()
#define ff first
#define ss second
#define all(a) a.begin(),a.end()
#define pb push_back
 
const int mod = ll(1e9)+7; //(b + (a%b)) % b (to mod -1%(10^9+7) correctly in c++ its -1 but its suppose to be 10^9+6
const ll MOD = 998244353;  // (a%mod)*(binpow(b,mod-2,mod) = (a/b)%mod
const int N = ll(4e5)+100;
const int M = ll(2e5) + 100;
const long long inf = 5e18;
const long double eps = 1e-15L;
 
ll lcm(ll a, ll b) { return (a / __gcd(a,b))*b; }
 
ll binpow(ll a, ll b, ll m) { ll res=1; a %= m; while(b>0){ if(b&1)res=(res * a) % m; a=(a * a) % m; b/=2; } return res%m;}
 
void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }

#define int ll
 
void Baizho() {
	int n; cin>>n;
	int a[n + 1], b[n + 1];
	for(int i = 1; i <= n; i ++) cin>>a[i];
	int ans = 0;
	for(int k = 0; k < 30; k ++) {
		for(int i = 1; i <= n; i ++) b[i] = a[i] % (1ll << (k + 1));
		sort(b + 1, b + n + 1);
		int cnt = 0;
		for(int i = 1; i <= n; i ++) {
			int l = i, r = n, usel, user;
			while(l <= r) {
				int mid = (l + r) / 2;
				if(b[i] + b[mid] >= (1ll << k)) r = mid - 1;
				else l = mid + 1;
			}
			usel = r + 1;
			
			l = i, r = n;
			while(l <= r) {
				int mid = (l + r) / 2;
				if(b[i] + b[mid] < (1ll << (k + 1))) l = mid + 1;
				else r = mid - 1;
			}
			user = l - 1;
			cnt += (user - usel + 1);
			
			l = i, r = n, usel = 0, user = 0;
			while(l <= r) {
				int mid = (l + r) / 2;
				if(b[i] + b[mid] >= (1ll << k) + (1ll << k + 1)) r = mid - 1;
				else l = mid + 1;
			}
			usel = r + 1;
			
			l = i, r = n;
			while(l <= r) {
				int mid = (l + r) / 2;
				if(b[i] + b[mid] < (1ll << (k + 2))) l = mid + 1;
				else r = mid - 1;
			}
			user = l - 1;
			cnt += (user - usel + 1);
		}
		if(cnt & 1) ans ^= (1ll << k);
	}
	cout<<ans<<"\n";
}
 
signed main() {		
// 	Freopen("nondec");
    ios_base::sync_with_stdio(false);   
    cin.tie(0);cout.tie(0); 
//   	precalc();
   	
    int ttt = 1;
//    cin>>ttt;
 
    for(int i=1; i<=ttt; i++) {Baizho(); }
}

Compilation message (stderr)

xorsum.cpp: In function 'void Baizho()':
xorsum.cpp:69:48: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
   69 |     if(b[i] + b[mid] >= (1ll << k) + (1ll << k + 1)) r = mid - 1;
      |                                              ~~^~~
xorsum.cpp: In function 'void Freopen(std::string)':
xorsum.cpp:35:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 | void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }
      |                           ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
xorsum.cpp:35:76: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 | void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }
      |                                                                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 38 / 38
• Subtask 5: 0 / 23