Merge pull request #480 from ishikasinha-d/master

Maximum Subset XOR in cpp

Author: smv1999

Bit Manipulation/max_subset_XOR.cpp

@@ -0,0 +1,64 @@
+// Given an array of N positive integers. Find an integer denoting the maximum XOR subset value in the given array.
+// Time complexity: O(n)
+
+
+#include<bits/stdc++.h>
+#define fl(i,a,b) for(i=a;i<b;i++)
+#define fast ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
+using namespace std;
+typedef long long int ll;
+
+ll maxSubsetXOR(ll set[], ll n)
+{
+    ll index=0, max_pos, max;
+    for (ll i = 31; i >= 0; i--)
+    {
+        max= LONG_MIN;
+        max_pos= index;
+         for (ll j = index; j < n; j++)
+        {
+            if ( (arr[j] & (1 << i)) != 0 && arr[j] > max )
+                     {
+                         max= arr[j];
+                         max_pos= j;
+                     }
+               
+        }
+        if (max == LONG_MIN)
+            continue;
+
+        swap(arr[index], arr[max_pos]);
+        max_pos = index;
+
+        for (ll j=0; j<n; j++)
+        {
+            if (j != max_pos &&  (arr[j] & (1 << i)) != 0)
+                arr[j] = arr[j] ^ arr[max_pos];
+        }
+        index++;
+    }
+    ll ans = 0;
+    for (ll i = 0; i < n; i++)
+        ans ^= arr[i];
+    return ans;
+}
+
+int main()
+{ 
+   fast;
+
+    #ifndef ONLINE_JUDGE
+    freopen("input.txt","r",stdin);
+    freopen("output.txt","w",stdout);
+    #endif
+
+    ll n; cin>>n;
+    ll arr[n];
+    for(auto &x: arr)
+        cin>>x;
+     
+    cout << maxSubsetXOR(arr, n);
+    
+    return 0;
+
+}

README.md

@@ -24,6 +24,7 @@ This repository contains all the popular Competitive Programming questions and I
  <li><a href="https://github.com/smv1999/CompetitiveProgrammingQuestionBank/tree/master/General%20Questions">General Questions</a></li>
  <li><a href="https://github.com/smv1999/CompetitiveProgrammingQuestionBank/tree/master/Greedy">Greedy</a></li>
  <li><a href="https://github.com/smv1999/CompetitiveProgrammingQuestionBank/tree/master/Hackerrank%20solutions">HackerRank Solutions</a></li>
+ <li><a href="https://github.com/smv1999/CompetitiveProgrammingQuestionBank/tree/master/Hashing">Hashing</a></li>
  <li><a href="https://github.com/smv1999/CompetitiveProgrammingQuestionBank/tree/master/Numbers">Numbers</a></li>
  <li><a href="https://github.com/smv1999/CompetitiveProgrammingQuestionBank/tree/master/OOPs">OOPs</a></li>
  <li><a href="https://github.com/smv1999/CompetitiveProgrammingQuestionBank/tree/master/Passwords">Passwords</a></li>