Cherry Pickup LeetCode solution in JavaScript

1
var cherryPickup = function (grid) {
2
  let result = 0,
3
    N = grid.length,
4
    cache = {},
5
    cherries;
6

7
  const solve = (x1, y1, x2, y2) => {
8
    if (x1 === N - 1 && y1 === N - 1)
9
      return grid[x1][y1] !== -1 ? grid[x1][y1] : -Infinity;
10
    if (
11
      x1 > N - 1 ||
12
      y1 > N - 1 ||
13
      x2 > N - 1 ||
14
      y2 > N - 1 ||
15
      grid[x1][y1] === -1 ||
16
      grid[x2][y2] === -1
17
    )
18
      return -Infinity;
19

20
    let lookup_key = `${x1}:${y1}:${x2}:${y2}`;
21
    if (cache[lookup_key]) return cache[lookup_key];
22

23
    if (x1 === x2 && y1 === y2) cherries = grid[x1][y1];
24
    else cherries = grid[x1][y1] + grid[x2][y2];
25

26
    result =
27
      cherries +
28
      Math.max(
29
        solve(x1 + 1, y1, x2 + 1, y2),
30
        solve(x1, y1 + 1, x2, y2 + 1),
31
        solve(x1 + 1, y1, x2, y2 + 1),
32
        solve(x1, y1 + 1, x2 + 1, y2)
33
      );
34

35
    cache[lookup_key] = result;
36
    return result;
37
  };
38

39
  result = solve(0, 0, 0, 0);
40
  return result > 0 ? result : 0;
41
};