You are a traveller on a 2d grid. You begin in the top-left corner and your goa is to travel to the bottom-right corner. You may only move down/right

grid_traveler.js

const gridTraveler = (m, n, memo={}) => {
    const key = `${m},${n}`
    if (key in memo) return memo[key]
    if (m === 1 && n === 1) return 1
    if (m === 0 || n === 0) return 0
    memo[key] = gridTraveler(m - 1, n, memo) + gridTraveler(m, n - 1, memo)
    return memo[key]
}
console.log(2,2)  // 2
console.log(gridTraveler(18,18))  //2333606220