Submission #1023408

#	Time	Username	Problem	Language	Result	Execution time	Memory
1023408		NintsiChkhaidze	XOR Sum (info1cup17_xorsum)	C++17	45 / 100	459 ms	49908 KiB

xorsum

#include <bits/stdc++.h>
#include <ostream>
#define pb push_back
#define s second
#define f first
#define pb push_back
#define pii pair <int,int>
#define ll long long
#define left h*2,l,(l + r)/2
#define right h*2+1,(l + r)/2 + 1,r
#define int ll
using namespace std;
 
const int N = 1e6 + 5,inf = 1e9;
int a[N];
pii arr[N],b[N];
bool fix[N];

signed main() {
  ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
  
  int n;
  cin>>n;

  for (int i = 1; i <= n; i++){
    cin >> a[i];
  }

  for (int j = 1; j <= n; j++)
      arr[j] = {(a[j] & ((1<<(0 + 1)) - 1)),j};
  sort(arr+1,arr+n+1);

  int ans=0,add=0;
  for (int i = 0; i <= 30; i++){
    int m = n;
    for (int j = 1; j <= n; j++){
      int bb = ((a[arr[j].s] >> i) & 1);
      if(bb > 0) fix[j] = 1,arr[++m] = arr[j];
    }

    int idx = 0;
    for (int j = 1; j <= m; j++){
      if (fix[j]) continue;
      b[++idx] = arr[j];
    }

    for (int j = 1; j <= n; j++){
      int x = b[j].s;
      arr[j] = {(a[x] & ((1<<(i + 1)) - 1)),x};
      fix[j] = 0;
    }

    vector <pair <pii,int>  > v;
    for (int j = 1; j <= n; j++){
      int sum = ((arr[j].f + arr[n].f) >> i) & 3;
      if (v.size() && v.back().s == sum) v.back().f.s += 1;
      else {
        v.pb({{j,j},sum});
      }
    }

    int cnt = 0,add = 0;
    int r0 = 0,r1 = 0,r2 = 0;

    for (int j = n; j >= 1; j--){
        while (r0 + 1 <= n && (((arr[j].f + arr[r0 + 1].f) >> i) & 3) <= 0) r0++;
        while (r1 + 1 <= n && (((arr[j].f + arr[r1 + 1].f) >> i) & 3) <= 1) r1++;
        while (r2 + 1 <= n && (((arr[j].f + arr[r2 + 1].f) >> i) & 3) <= 2) r2++;

        int l = max(j,r0 + 1),r = r1;
        cnt += max(0LL,r - l + 1);

        l = max(j,r2 + 1),r = n;
        cnt += max(0LL,r - l + 1);
    }

    if (cnt & 1) ans |= (1LL<<i);
  }

  cout<<ans;
}

Compilation message (stderr)

xorsum.cpp: In function 'int main()':
xorsum.cpp:62:17: warning: unused variable 'add' [-Wunused-variable]
   62 |     int cnt = 0,add = 0;
      |                 ^~~
xorsum.cpp:33:13: warning: unused variable 'add' [-Wunused-variable]
   33 |   int ans=0,add=0;
      |             ^~~

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