Submission #496981

#	Time	Username	Problem	Language	Result	Execution time	Memory
496981		mansur	XOR Sum (info1cup17_xorsum)	C++14	56 / 100	1120 ms	16308 KiB

xorsum

#include<bits/stdc++.h>	
 
#pragma optimize ("g",on)
#pragma GCC optimize ("inline")
#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#pragma GCC optimize ("03")
#pragma GCC target ("sse,sse2,sse3,ssse3,sse4,popcnt,abm,avx2,mmx,fma,avx,tune=native")
#pragma comment(linker, "/stack:200000000")
 
//01001101 01100001 01101011 01101000 01100001  01100111 01100001 01111001 
 
using namespace std;
 
#define all(a) a.begin(), a.end()                                                   
#define rall(a) a.rbegin(), a.rend()
#define ll long long
#define pb push_back
#define sz(a) a.size()
#define nl '\n'
#define popb pop_back()                                                                   
#define ld double
#define ull unsigned long long
#define ff first                                         
#define ss second  
#define fix fixed << setprecision
#define pii pair<int, int>                          
#define E exit (0)
#define int long long
 
const int inf = 1e15, N = 1e5, mod = 998244353;                    
 
vector<pii> dir = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
 
main() {                                                         
	//freopen("cowrect.in", "r", stdin);                                                                                     
	//freopen("cowrect.out", "w", stdout);                                                                                     
	ios_base::sync_with_stdio(NULL);                                                                                        
	cin.tie(NULL);
	int n;
	cin >> n;
	int a[n + 1], ans = 0;
	for (int i = 1; i <= n; i++) cin >> a[i];
	if (n <= N) {
		for (int i = 1; i <= n; i++) {
			for (int j = i; j <= n; j++) {
				ans ^= a[i] + a[j];
			}
		}
		cout << ans;
	}else {
		vector<int> cnt(4001);
		for (int i = 1; i <= n; i++) {
			cnt[a[i]]++;
		}
		for (int i = 1; i <= 4000; i++) {
			for (int j = i; j <= 4000; j++) {
				int cur = cnt[i] * cnt[j];
				if (i == j) cur = cnt[i] * (cnt[i] + 1) / 2;
				if (cur & 1) ans ^= i + j;
			}
		}
		cout << ans;
	}
}

Compilation message (stderr)

xorsum.cpp:3: warning: ignoring '#pragma optimize ' [-Wunknown-pragmas]
    3 | #pragma optimize ("g",on)
      | 
xorsum.cpp:9: warning: ignoring '#pragma comment ' [-Wunknown-pragmas]
    9 | #pragma comment(linker, "/stack:200000000")
      | 
xorsum.cpp:35:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   35 | main() {
      | ^~~~

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