1442.CountTriplets.cs

// 1442. Count Triplets That Can Form Two Arrays of Equal XOR
// Given an array of integers arr.
// We want to select three indices i, j and k where (0 <= i < j <= k < arr.length).
// Let's define a and b as follows:
// a = arr[i] ^ arr[i + 1] ^ ... ^ arr[j - 1]
// b = arr[j] ^ arr[j + 1] ^ ... ^ arr[k]
// Note that ^ denotes the bitwise-xor operation.
// Return the number of triplets (i, j and k) Where a == b.

// Example 1:
// Input: arr = [2,3,1,6,7]
// Output: 4
// Explanation: The triplets are (0,1,2), (0,2,2), (2,3,4) and (2,4,4)
// Example 2:
// Input: arr = [1,1,1,1,1]
// Output: 10

// Constraints:
// 1 <= arr.length <= 300
// 1 <= arr[i] <= 108

public class Solution {
    public int CountTriplets(int[] arr) {
        int count = 0;
        for(int i = 0; i < arr.Length; i++){
            int val = arr[i];
            for(int k = i+1; k < arr.Length; k++){
                val ^= arr[k];
                if(val == 0)
                    count += (k-i);
            }
        }
        return count;
    }
}