Submission #159361

#	Time	Username	Problem	Language	Result	Execution time	Memory
159361		mrtsima22	XOR Sum (info1cup17_xorsum)	C++17	45 / 100	1669 ms	12024 KiB

xorsum

#pragma GCC optimize "-O3"
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
inline int bin(){
	int x=0;char ch=getchar();
	while (ch<'0'||ch>'9') ch=getchar();
	while (ch>='0'&&ch<='9') x=(x<<3)+(x<<1)+ch-'0',ch=getchar();
	return x;
}
void countSort(int arr[], int n, int exp) 
{ 
    int output[n]; // output array 
    int i, count[10] = {0}; 
  
    // Store count of occurrences in count[] 
    for (i = 0; i < n; i++) 
        count[ (arr[i]/exp)%10 ]++; 
  
    // Change count[i] so that count[i] now contains actual 
    //  position of this digit in output[] 
    for (i = 1; i < 10; i++) 
        count[i] += count[i - 1]; 
  
    // Build the output array 
    for (i = n - 1; i >= 0; i--) 
    { 
        output[count[ (arr[i]/exp)%10 ] - 1] = arr[i]; 
        count[ (arr[i]/exp)%10 ]--; 
    } 
  
    // Copy the output array to arr[], so that arr[] now 
    // contains sorted numbers according to current digit 
    for (i = 0; i < n; i++) 
        arr[i] = output[i]; 
} 
void radixsort(int arr[], int n) 
{ 
    // Find the maximum number to know number of digits 
    int m = 100000000; 
  
    // Do counting sort for every digit. Note that instead 
    // of passing digit number, exp is passed. exp is 10^i 
    // where i is current digit number 
    for (int exp = 1;  exp<= m; exp *= 10) 
        countSort(arr, n, exp); 
}
const int M=29;
int n,a[1000004],b[1000004];
int c[39],ans;
inline void work(int x,int y,int &k,int &K){
	int l=-1,r=-1;
	for(int o=n-1;o>=0;o--){
		while(l+1<n&&b[l+1]+b[o]<x) l++;
		while(r+1<n&&b[r+1]+b[o]<=y) r++;
		if(o>l&&o<=r) K++;
		if(l<=r)
			k+=(r-l);
	}
}
int main(){
	ios::sync_with_stdio(false);
for(int i=1;i<=M;i++){
	c[i]=(1<<(i+1))-1;
}
n=bin();
for(int i=0;i<n;i++){
	a[i]=bin();
}
for(int i=1;i<=M;i++){
	for(int j=0;j<n;j++){
		b[j]=c[i]&a[j];
	}
//	sort(b,b+n);
	radixsort(b,n);
	int b1=(1<<(i));
	int b2=((1<<(i+1))-1);
	int B1=b1+(1<<(i+1));
	int B2=((1<<(i+2))-2);
	int k=0,K=0;
	work(b1,b2,k,K);
	work(B1,B2,k,K);
	k-=K;
	k/=2;
	k+=K;
//	cout<<k<<endl;
	if(k&1){
		ans|=(1<<(i));
	}
}
int k=0;
for(int i=0;i<n;i++){
	if(a[i]&1) k++;
}
if((k*(n-k))&1){
	ans++;
}
cout<<ans<<endl;

}

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