Today I have done leetcode's January LeetCoding Challenge with cpp.

January LeetCoding Challenge 20

Description

Construct the Minimum Bitwise Array I

You are given an array nums consisting of n prime integers.

You need to construct an array ans of length n, such that, for each index i, the bitwise OR of ans[i] and ans[i] + 1 is equal to nums[i], i.e. ans[i] OR (ans[i] + 1) == nums[i].

Additionally, you must minimize each value of ans[i] in the resulting array.

If it is not possible to find such a value for ans[i] that satisfies the condition, then set ans[i] = -1.

Example 1:

Input: nums = [2,3,5,7]

Output: [-1,1,4,3]

Explanation:

For i = 0, as there is no value for ans[0] that satisfies ans[0] OR (ans[0] + 1) = 2, so ans[0] = -1.
For i = 1, the smallest ans[1] that satisfies ans[1] OR (ans[1] + 1) = 3 is 1, because 1 OR (1 + 1) = 3.
For i = 2, the smallest ans[2] that satisfies ans[2] OR (ans[2] + 1) = 5 is 4, because 4 OR (4 + 1) = 5.
For i = 3, the smallest ans[3] that satisfies ans[3] OR (ans[3] + 1) = 7 is 3, because 3 OR (3 + 1) = 7.

Example 2:

Input: nums = [11,13,31]

Output: [9,12,15]

Explanation:

For i = 0, the smallest ans[0] that satisfies ans[0] OR (ans[0] + 1) = 11 is 9, because 9 OR (9 + 1) = 11.
For i = 1, the smallest ans[1] that satisfies ans[1] OR (ans[1] + 1) = 13 is 12, because 12 OR (12 + 1) = 13.
For i = 2, the smallest ans[2] that satisfies ans[2] OR (ans[2] + 1) = 31 is 15, because 15 OR (15 + 1) = 31.

Constraints:

1 <= nums.length <= 100
2 <= nums[i] <= 1000
nums[i] is a prime number.

Solution

constexpr auto table = []{
  array<int, 10001> arr;
  arr.fill(-1);
  for(int i = 0; i < 1001; ++i) {
    int pos = (i | (i + 1));
    if(arr[pos] == -1) arr[pos] = i;
  }
  return arr;
}();
class Solution {
public:
  vector<int> minBitwiseArray(vector<int>& nums) {
    int sz = nums.size();
    vector<int> answer(sz);
    for(int i = 0; i < sz; ++i) {
      answer[i] = table[nums[i]];
    }
    return answer;
  }
};

// Accepted
// 658/658 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 55.03 % of cpp submissions (25.2 MB)

2026-01-20 Daily Challenge

January LeetCoding Challenge 20

Description

Solution