grid.js

class Grid {
    constructor() {
        // Store grid in lookup table to allow for "infinite" room.
        this.grid = { '1,1': 20151125 };
    }

    // Note: this is slow / memory heavy for large row / col values!
    fillTo({ row, column } = {}) {
        let prev_value = this.grid['1,1'];
        const final_cell_key = `${column},${row}`;

        // The first code is 20151125.
        // After that, each code is generated by taking the previous one,
        // multiplying it by 252533, and then keeping the remainder from
        // dividing that value by 33554393

        let x = 1,
            y = 2;
        while (this.grid[final_cell_key] == null) {
            while (y > 0) {
                let current_cell = `${x},${y}`;
                let new_value = (prev_value * 252533) % 33554393;
                this.grid[current_cell] = new_value;
                prev_value = new_value;

                y--;
                x++;
            }

            y = x;
            x = 1;
        }

        return this.grid[final_cell_key];
    }

    getValueAt({ row, column } = {}) {
        let prev_value = 20151125;

        // The first code is 20151125.
        // After that, each code is generated by taking the previous one,
        // multiplying it by 252533, and then keeping the remainder from
        // dividing that value by 33554393

        let x = 1,
            y = 2;
        while (true) {
            while (y > 0) {
                let new_value = (prev_value * 252533) % 33554393;

                if (x === column && y === row) {
                    return new_value;
                }

                prev_value = new_value;

                y--;
                x++;
            }

            y = x;
            x = 1;
        }
    }

    printArray({ row, column }) {
        let grid = Array(row)
            .fill()
            .map(r => Array(column).fill());
        for (let y = 1; y <= row; y++) {
            for (let x = 1; x <= column; x++) {
                grid[y - 1][x - 1] = this.grid[`${x},${y}`];
            }
        }

        console.log(grid);
    }
}

module.exports = Grid;