Leetcode 1829

Questions

You are given a sorted array nums of n non-negative integers and an integer maximumBit. You want to perform the following query n times:

1. Find a non-negative integer k < 2maximumBit such that nums[0] XOR nums[1] XOR ... XOR nums[nums.length-1] XOR k is maximized. k is the answer to the ith query.
2. Remove the last element from the current array nums.

Return an array answer, where answer[i] is the answer to the ith query.

Example 1:

Input: nums = [0,1,1,3], maximumBit = 2 Output: [0,3,2,3] Explanation: The queries are answered as follows: 1st query: nums = [0,1,1,3], k = 0 since 0 XOR 1 XOR 1 XOR 3 XOR 0 = 3. 2nd query: nums = [0,1,1], k = 3 since 0 XOR 1 XOR 1 XOR 3 = 3. 3rd query: nums = [0,1], k = 2 since 0 XOR 1 XOR 2 = 3. 4th query: nums = [0], k = 3 since 0 XOR 3 = 3.

Example 2:

Input: nums = [2,3,4,7], maximumBit = 3 Output: [5,2,6,5] Explanation: The queries are answered as follows: 1st query: nums = [2,3,4,7], k = 5 since 2 XOR 3 XOR 4 XOR 7 XOR 5 = 7. 2nd query: nums = [2,3,4], k = 2 since 2 XOR 3 XOR 4 XOR 2 = 7. 3rd query: nums = [2,3], k = 6 since 2 XOR 3 XOR 6 = 7. 4th query: nums = [2], k = 5 since 2 XOR 5 = 7.

Example 3:

Input: nums = [0,1,2,2,5,7], maximumBit = 3 Output: [4,3,6,4,6,7]

Constraints:

• nums.length == n
• 1 <= n <= 105
• 1 <= maximumBit <= 20
• 0 <= nums[i] < 2maximumBit
• nums​​​ is sorted in ascending order.

My Approaches

class Solution {
public:
    vector<int> getMaximumXor(vector<int>& nums, int maximumBit) {
        int xored(0);
        vector<int> ans;
        for(auto k: nums){
            xored = xored ^ k;
            int elem = ~xored;
            ans.insert(ans.begin(), elem+(pow(2, maximumBit)));
        }
        return ans;
    }
};

I tried not to change integer to binary representation. I used bitwise operation to get the maximum XOR value. Variable xored is the result of XOR operation of all elements in the array. Then I did XOR operation for each element in the array, and elem is the reverse of xored.

Then, I added elem to the beginning of the ans array.

This approach is not efficient because of the time complexity of the insert operation.