Submission #673988

#	Time	Username	Problem	Language	Result	Execution time	Memory
673988		QwertyPi	XOR Sum (info1cup17_xorsum)	C++14	Compilation error	0 ms	0 KiB

xorsum

#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

using namespace std;

const int N = 1e6 + 11;
int a[N], b0[N], b0n, b1[N], b1n;

int main(){
	int n; cin >> n;
	for(int i = 0; i < n; i++){
		cin >> a[i];
	}
	int ans = 0;
	for(int s = 0; s <= 29; s++){
		int c = 0;
		b0n = b1n = 0;
		for(int j = 0; j < n; j++){
			if(a[i] & (1 << s)) b0[b0n++] = a[i] % (1 << s);
			else b1[b1n++] = a[i] % (1 << s);
		}
		sort(b0, b0 + b0n); sort(b1, b1 + b1n);
		int r = b0n;
		for(int l = 0; l < b0n; l++){
			r = max(r, l + 1);
			while(r - 1 > l && b0[l] + b0[r - 1] >= (1 << s)) r--;
			c += b0n - r;
		}
		
		r = b1n;
		for(int l = 0; l < b1n; l++){
			r = max(r, l + 1);
			while(r - 1 > l && b1[l] + b1[r - 1] >= (1 << s)) r--;
			c += b1n - r;
		}
		
		r = b1n;
		for(int l = 0; l < b0n; l++){
			r = max(r, l + 1);
			while(r - 1 > l && b0[l] + b1[r - 1] >= (1 << s)) r--;
			c += b1n - r;
		}
		ans ^= (1 << s) * (c % 2); 
	}
	cout << ans << endl;
}

Compilation message (stderr)

xorsum.cpp: In function 'int main()':
xorsum.cpp:20:9: error: 'i' was not declared in this scope
   20 |    if(a[i] & (1 << s)) b0[b0n++] = a[i] % (1 << s);
      |         ^