LeetCode: 1222. Queens That Can Attack the King
On an 8x8 chessboard, there can be multiple Black Queens and one White King.
Given an array of integer coordinates queens that represents the positions of the Black Queens, and a pair of coordinates king that represent the position of the White King, return the coordinates of all the queens (in any order) that can attack the King.
Example
Input: queens = [[0,1],[1,0],[4,0],[0,4],[3,3],[2,4]], king = [0,0]
Output: [[0,1],[1,0],[3,3]]
Explanation:
The queen at [0,1] can attack the king cause they're in the same row.
The queen at [1,0] can attack the king cause they're in the same column.
The queen at [3,3] can attack the king cause they're in the same diagnal.
The queen at [0,4] can't attack the king cause it's blocked by the queen at [0,1].
The queen at [4,0] can't attack the king cause it's blocked by the queen at [1,0].
The queen at [2,4] can't attack the king cause it's not in the same row/column/diagnal as the king.
My solution:
/**
* @param {number[][]} queens
* @param {number[]} king
* @return {number[][]}
*/
var queensAttacktheKing = function(queens, king) {
//get king x,y coordinate
var x = king[0];
var y = king[1];
//totally 8 directions, index 0 - 7
var direction = [null, null, null, null,
null, null, null, null];
//compare
for( var i = 0; i < queens.length; i++){
//compare 'top'
if( queens[i][1] == y && queens[i][0] < x){
if((direction[0] == null) || (direction[0][0] < queens[i][0])){
direction[0] = queens[i];
}
}
//compare 'top-right'
if( (queens[i][1] - y) == ( x - queens[i][0]) && ( (queens[i][1] - y) > 0)){
if((direction[1] == null) || (direction[1][0] < queens[i][0])){
direction[1] = queens[i];
}
}
//compare 'right'
if( queens[i][0] == x && queens[i][1] > y ){
if((direction[2] == null) || (direction[2][1] > queens[i][1])){
direction[2] = queens[i];
}
}
//compare 'right-bottom'
if( (queens[i][1] - y) == ( queens[i][0] - x) && ( (queens[i][0] - x) > 0)){
if((direction[3] == null) || (direction[3][0] > queens[i][0])){
direction[3] = queens[i];
}
}
//compare 'bttom'
if( queens[i][1] == y && queens[i][0] > x){
if((direction[4] == null)||(direction[4][0] > queens[i][0])){
direction[4] = queens[i];
}
}
//compare 'left-bottom'
if( ( y - queens[i][1] ) == ( queens[i][0] - x ) && ( (y - queens[i][1]) > 0)){
if((direction[5] == null)||(direction[5][0] > queens[i][0])){
direction[5] = queens[i];
}
}
//compare 'left'
if( queens[i][0] == x && queens[i][1] < y){
if((direction[6] == null) || (direction[6][1] < queens[i][1])){
direction[6] = queens[i];
}
}
//compare 'top-left'
if( ( y - queens[i][1] ) == ( x - queens[i][0]) && ( (x - queens[i][0]) > 0) ){
if((direction[7] == null) || (direction[7][1] < queens[i][1])){
direction[7] = queens[i];
}
}
}
var filtered = direction.filter(function(value, index, arr){
return value != null;
});
return filtered;
};