Submission #1115086

#	Time	Username	Problem	Language	Result	Execution time	Memory
1115086		12345678	XOR Sum (info1cup17_xorsum)	C++17	0 / 100	253 ms	20816 KiB

xorsum

#include <bits/stdc++.h>

using namespace std;

#define ll long long

const int vx=4e6+5, nx=1e6+5;

int n, dp[vx], f[vx], a[nx], ans;

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n;
    for (int i=1; i<=n; i++) cin>>a[i];
    for (int bit=0; bit<21; bit++)
    {
        ll cur=0, res=0, mod=(1<<(bit+1));
        for (int i=1; i<=n; i++) f[a[i]%mod]++;
        for (int i=0; i<(1<<bit); i++) cur+=f[i];
        dp[0]=cur;
        for (int i=1; i<mod; i++)
        {
            cur-=f[i-1];
            cur+=f[(i+(1<<bit))%mod];
            dp[i]=cur;
        }
        for (int i=1; i<=n; i++) res+=dp[(((-a[i])%mod)+mod)%mod];
        if (res%2) ans+=(1<<bit);
        for (int i=1; i<=n; i++) f[a[i]%mod]--;
    }
    cout<<ans;
}

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