Not for 63 days. The biggest XOR

 

 

class Solution {
    //  The highest bit number is  30
    static final int HIGH_BIT = 30;

    public int findMaximumXOR(int[] nums) {
        int x = 0;
        for (int k = HIGH_BIT; k >= 0; --k) {
            Set<Integer> seen = new HashSet<Integer>();
            //  Will all  pre^k(a_j)  Put it in the hash table 
            for (int num : nums) {
                //  If you just want to keep it from the top to the bottom  k  The part that ends with two binary bits 
                //  Just move it to the right  k  position 
                seen.add(num >> k);
            }

            //  at present  x  From the top to the bottom  k+1  The part that ends with two binary bits 
            //  We will  x  Of the  k  Two binary positions are  1, That is to say  x = x*2+1
            int xNext = x * 2 + 1;
            boolean found = false;
            
            //  enumeration  i
            for (int num : nums) {
                if (seen.contains(xNext ^ (num >> k))) {
                    found = true;
                    break;
                }
            }

            if (found) {
                x = xNext;
            } else {
                //  If you don't find one that satisfies the equation  a_i  and  a_j, that  x  Of the  k  A binary bit can only be  0
                //  That is to say  x = x*2
                x = xNext - 1;
            }
        }
        return x;
    }
}

 author ：LeetCode-Solution
 link ：https://leetcode.cn/problems/ms70jA/solution/zui-da-de-yi-huo-by-leetcode-solution-hr7m/
 source ： Power button （LeetCode）
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