Find bitwise OR of all possible sub-arrays
Given an array A of size N where, 
. The task is to find the OR of all possible sub-arrays of A and then the OR of all these results.
Examples:
Input : 1 4 6
Output : 7
All possible subarrays are
{1}, {1, 4}, {4, 6} and {1, 4, 6}
ORs of these subarrays are 1, 5, 6
and 7. OR of these ORs is 7.
Input : 10 100 1000
Output : 1006
Approach: In SET 1 we have seen how to find bitwise AND of all possible subarrays. Similar approach is also aplicable here.
The Naive solution is to find the OR of all the sub-arrays and then output the OR of their results. This will lead to O(N2) solution.
Efficient Solution: Using the property that 
i:e it doesn’t matter how many times an element comes, it’s ORing will be counted as one only. Thus our problem boils down to finding the OR of all the elements of the array.
Below is the implementation of above approach.
C++
// C++ program to find OR of all the sub-arrays #include <bits/stdc++.h> using namespace std; // function to return OR of sub-arrays int OR(int a[], int n) { int ans = a[0]; for (int i = 1; i < n; ++i) ans |= a[i]; return ans; } // Driver program int main() { int a[] = { 1, 4, 6 }; int n = sizeof(a) / sizeof(a[0]); // print OR of all subarrays cout << OR(a, n); return 0; } |
chevron_right
filter_none
Java
// Java program to find OR of // all the sub-arrays class GFG { // function to return OR // of sub-arrays static int OR(int a[],int n) { int ans = a[0]; int i; for(i = 1; i < n; i++) { ans |= a[i]; } return ans; } // Driver Code public static void main(String args[]) { int a[] = { 1, 4, 6}; int n = a.length; // print OR of all subarrays System.out.println(OR(a, n)); } } // This code is contributed // by ANKITRAI1 |
chevron_right
filter_none
Python3
# Python3 program to find OR of all the sub-arrays # function to return OR of sub-arrays def OR(a, n): ans = a[0] for i in range(1,n): ans |= a[i] return ans # Driver Code if __name__=='__main__': a = [1, 4, 6] n = len(a) # print OR of all subarrays print(OR(a, n)) # This code is contributed # by Shashank_Sharma |
chevron_right
filter_none
C#
// C# program to find OR of // all the sub-arrays using System; class GFG { // function to return OR // of sub-arrays static int OR(int[] a, int n) { int ans = a[0]; int i; for(i = 1; i < n; i++) { ans |= a[i]; } return ans; } // Driver Code public static void Main() { int[] a = { 1, 4, 6}; int n = a.Length; // print OR of all subarrays Console.Write(OR(a, n)); } } // This code is contributed // by ChitraNayal |
chevron_right
filter_none
PHP
<?php // PHP program to find OR // of all the sub-arrays // function to return OR // of sub-arrays function O_R($a, $n) { $ans = $a[0]; for ($i = 1; $i < $n; ++$i) $ans |= $a[$i]; return $ans; } // Driver Code $a = array( 1, 4, 6 ); $n = count($a); // print OR of all subarrays echo O_R($a, $n); // This code is contributed // by inder_verma ?> |
chevron_right
filter_none
Output:
7
Time Complexity: O(N)
Recommended Posts:
- Sum of bitwise OR of all subarrays
- Sum of bitwise AND of all subarrays
- Number of subarrays have bitwise OR >= K
- Sum of Bitwise-OR of all subarrays of a given Array | Set 2
- Count distinct Bitwise OR of all Subarrays
- Find subsequences with maximum Bitwise AND and Bitwise OR
- Total pairs in an array such that the bitwise AND, bitwise OR and bitwise XOR of LSB is 1
- Find number of subarrays with even sum
- Differences between number of increasing subarrays and decreasing subarrays in k sized windows
- Find number of subarrays with XOR value a power of 2
- Find if array can be divided into two subarrays of equal sum
- Find the count of Strictly decreasing Subarrays
- Find bitwise AND (&) of all possible sub-arrays
- Leftover element after performing alternate Bitwise OR and Bitwise XOR operations on adjacent pairs
- Find an element which divides the array in two subarrays with equal product
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.
- Flipping Sign Problem | Lazy Propagation Segment Tree
- Maximum previous and next element product
- Sort an array according to absolute difference with given value using Functors
- Minimum Circles needed to be removed so that all remaining circles are non intersecting
- Minimum count of elements that sums to a given number
- Array containing power of 2 whose XOR and Sum of elements equals X
- Find an N x N grid whose xor of every row and column is equal
- Maximum XOR of Two Numbers in an Array
- Check if a cycle of length 3 exists or not in a graph that satisfy a given condition
- Check whether bitwise AND of N numbers is Even or Odd
