#3670

Maximum Product of Two Integers With No Common Bits

Medium
ArrayDynamic ProgrammingBit ManipulationBit ManipulationDynamic Programming
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Approaches

Brute ForceOptimal
Complexity Comparison
Brute ForceOptimal Solution
Time
O(n²)
O(n + B²)
Space
O(1)
O(B)
💡

Intuition

Time O(n + B²)Space O(B)

Use bit masks to categorize numbers and find the maximum product without common bits efficiently.

⚙️

Algorithm

3 steps
  1. 1Step 1: Create a list to store the maximum number for each bitmask (up to 2^20 for 1 ≤ nums[i] ≤ 10^6).
  2. 2Step 2: For each number, update the corresponding bitmask with the maximum value found.
  3. 3Step 3: Iterate through all pairs of masks, checking for no common bits and calculating the product.
solution.py10 lines
1def maxProduct(nums):
2    max_mask = [0] * (1 << 20)
3    for num in nums:
4        max_mask[num] = max(max_mask[num], num)
5    max_product = 0
6    for i in range(len(max_mask)):
7        for j in range(i + 1, len(max_mask)):
8            if (i & j) == 0:
9                max_product = max(max_product, max_mask[i] * max_mask[j])
10    return max_product

Complexity note: We process each number once and check pairs of masks, where B is the bit-width (up to 20).

  • 1Bit manipulation helps efficiently check for common bits.
  • 2Using masks allows us to categorize numbers and maximize products.

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