Number of unique xor triplets ii

Array Math Bit Manipulation Enumeration

32.4% acceptance

Feb 25, 2026

You are given an integer array nums. A XOR triplet is defined as the XOR of three elements nums[i] XOR nums[j] XOR nums[k] where i <= j <= k. Return the number of unique XOR triplet values from all possible triplets (i, j, k).

Solution

Rust

Time O(n²)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn unique_xor_triplets(nums: Vec<i32>) -> i32 {
    // All values <= 1500 < 2048 = 2^11
    const MAX_VAL: usize = 2048;
    let mut s1 = [false; MAX_VAL]; // set of element values
    for &v in &nums {
      s1[v as usize] = true;
    }

    // s2 = { a XOR b | a, b in s1 }
    let mut s2 = [false; MAX_VAL];
    for a in 0..MAX_VAL {
      if !s1[a] { continue; }
      for b in 0..MAX_VAL {
        if !s1[b] { continue; }
        s2[a ^ b] = true;
      }
    }

    // s3 = { c XOR e | c in s2, e in s1 }
    let mut s3 = [false; MAX_VAL];
    for c in 0..MAX_VAL {
      if !s2[c] { continue; }
      for e in 0..MAX_VAL {
        if !s1[e] { continue; }
        s3[c ^ e] = true;
      }
    }

    s3.iter().filter(|&&v| v).count() as i32
  }
}