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SUBXOR - SubXor

SUBXOR - SubXor

Subarray Xor

Topic: Trie Tree 

Explanation 

Solution 01:


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#include <bits/stdc++.h>
using namespace std;
#define INF 1<<30
#define MAX 200005
#define FASTIO ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
typedef long long ll;


struct trie
{
  int L,R;
  int lft, rgt;

  trie(){
    L = R = 0;
    lft = rgt = -1;
  }
};

int Index = 0;

void Insert(int value, int idx, int depth, trie *tree)
{
  for(int i = depth-1; i >= 0; i--){
    int bit = (value >> i ) & 1;
    if(bit){
      tree[idx].R++;
      if(tree[idx].rgt == -1){
        tree[idx].rgt = ++Index;
        idx = Index;
      }
      else idx = tree[idx].rgt;
    }
    else{
      tree[idx].L++;
      if(tree[idx].lft == -1){
        tree[idx].lft = ++Index;
        idx = Index;
      }
      else idx = tree[idx].lft;
    }
  }
}

int Query(int value, int cmp, int idx, int depth, trie* tree)
{
  int ans = 0;
  for(int i = depth-1; i >= 0; i--){
    int vBit = (value >>i) & 1;
    int cBit = (cmp >> i) & 1;
    if(cBit){
      if(vBit){
        ans += tree[idx].R;
        idx = tree[idx].lft;
      }
      else{
        ans += tree[idx].L;
        idx = tree[idx].rgt;
      }
    }
    else{
      if(vBit) idx = tree[idx].rgt;
      else idx = tree[idx].lft;
    }
    if(idx == -1)break;
  }
  return ans;
}

int main()
{
    FASTIO
    ///*
    //double start_time = clock();
#ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
    freopen("error.txt", "w", stderr);
#endif
    //*/
    int T;
    cin >> T;
    while(T--){
      trie tree[MAX];
      Index = 0;
      int n,k;
      cin >> n >> k;
      int XOR = 0;
      ll  ans = 0;
      Insert(0,0,20,tree);
      for(int i =0; i < n; i++){
        int x;
        cin >> x;
        XOR = XOR ^ x;
        ans += Query(XOR,k,0,20,tree);
        Insert(XOR,0,20,tree);
      }
      cout << ans << endl;
    }
    

    //double end_time = clock();
    //printf( "Time = %lf ms\n", ( (end_time - start_time) / CLOCKS_PER_SEC)*1000);

    return 0;
}

Solution 02

Solution 03

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