15

DevGod

Elf Vtuber

Caution

DevGod needs to write an editorial for this problem!

js

let memo = new Map();
let blah = function(x,y){
  if(x==1 || y==1){return 1;}
  if(memo.has(x*21+y)){
    return memo.get(x*21+y);
  }
  memo.set( x*21+y, blah(x-1,y)+blah(x,y-1));
  return memo.get(x*21+y);
}

console.log( blah(21,21) );