the board problem

index.js

'use strict';

const example = [
  ['a', 'c', 'l', 'b'],
  ['r', 'e', 'b', 'u'],
  ['i', 'n', 'g', 's'],
  ['l', 'm', 'n', 'o']
];

console.log(contains(example, 'caring'));


//contains :: [[Char]] -> [Char] -> Bool
function contains(board, string) {
  let xs = string;
  let queue = initial(board, xs);

  if (queue.length === 0) return false;

  while (queue.length > 0) {
    const item = queue.shift();
    if (item[3].length === 0) {
      console.log(item[2]);
      return true
    }
    let ns = neighbor(board, item[0], item[1]).filter(d => {
      return !item[2].has(`${d[0]}-${d[1]}`) &&  item[3][0] === board[d[0]][d[1]];
    });
    for (let i = 0; i < ns.length; i++) {
      let newItem = [ns[i][0], ns[i][1], new Set([`${ns[i][0]}-${ns[i][1]}`, ...item[2]]), item[3].slice(1)];
      queue.push(newItem);
    }
  }
  return false;
}

// neighbor :: [[Char]] -> Int -> Int -> [[Int, Int]]
function neighbor(board, i, j) {
  const res = [
    [i - 1, j],
    [i + 1, j],
    [i, j - 1],
    [i, j + 1],
    [i - 1, j - 1],
    [i + 1, j + 1],
    [i - 1, j + 1],
    [i + 1, j - i]
  ].filter(d => {
    return d[0] > -1 && d[0] < board.length && d[1] > -1 && d[1] < board[0].length;
  });
  console.log(res);
  return res;
}


// initial :: [[Char]] -> Char -> [[Int, Int]]
function initial(board, xs) {
  const result = [];
  for (let i = 0; i < board.length; i++) {
    for (let j = 0; j < board[0].length; j++) {
      if (board[i][j] === xs[0]) {
        result.push([i, j, new Set([`${i}-${j}`]), xs.slice(1)]);
      }
    }
  }
  return result;
}

output is

[ [ 1, 1 ], [ 0, 0 ], [ 0, 2 ], [ 1, 2 ], [ 1, 1 ] ]
[ [ 1, 0 ], [ 0, 1 ], [ 1, 1 ], [ 1, 0 ] ]
[ [ 0, 0 ], [ 2, 0 ], [ 1, 1 ], [ 2, 1 ], [ 0, 1 ] ]
[ [ 0, 0 ], [ 2, 0 ], [ 1, 1 ], [ 2, 1 ], [ 0, 1 ] ]
[ [ 1, 0 ], [ 3, 0 ], [ 2, 1 ], [ 3, 1 ], [ 1, 1 ] ]
[ [ 1, 0 ], [ 3, 0 ], [ 2, 1 ], [ 3, 1 ], [ 1, 1 ] ]
[ [ 1, 1 ],
  [ 3, 1 ],
  [ 2, 0 ],
  [ 2, 2 ],
  [ 1, 0 ],
  [ 3, 2 ],
  [ 1, 2 ] ]
[ [ 1, 1 ],
  [ 3, 1 ],
  [ 2, 0 ],
  [ 2, 2 ],
  [ 1, 0 ],
  [ 3, 2 ],
  [ 1, 2 ] ]
Set { '2-2', '2-1', '2-0', '1-0', '0-0', '0-1' }
true