Solution for Leetcode problem 1222: Queens that can attack the king

In this problem, the question is which queen can attack the king given all the queens’ and king’s positions.

Problem statement

I took the simple approach of:

• Go from the king’s position
• Look in all directions one by one
• For each direction, I move through the positions one by one from the king until the position is occupied by a queen or the position is outside of the chess board
• To ease the search though the queens’ position array, I hashed the positions to integer x*8 + y, so the position lookup is constant time.

Technically, since the board size is constant, and queen[][] size is constant, there is no need for complexity analysis; but for a board N*N and a queens’ array of size M, the time complexity becomes O(N + M).

Solution:

class Solution {
    enum Step {
        
        R(1, 0),
        L(-1, 0),
        U(0, -1),
        D(0, 1),
        RU(1, -1),
        RD(1, 1),
        LU(-1, -1),
        LD(-1, 1);
        
        int x;
        int y;
        
        Step(int a, int b) {
            x = a;
            y = b;
        }
        
        int[] newPos(int[] pos) {
            int[] res = new int[2];
            res[0] = pos[0] + x;
            res[1] =…