You are given a 2D array of characters, and a target string. Return whether or not the target word exists in the matrix. Unlike a standard word search, the word must be either going left-to-right, or top-to-bottom in the matrix.

word_search.ts

const word_search = (arr:string[][], word: string) : boolean => {

  if(word.length > arr.length) return false;

  let horizontal = '';
  let vertical:{ [key: string]: string } = {};

  for(let i=0; i<arr.length;i++){
    for(let j=0; j<arr[i].length;j++){
      horizontal+= arr[i][j];
      if(!vertical[j]) vertical[j] = '';
      vertical[j] += arr[i][j];
    }
  }
  return horizontal.includes(word) || Object.values(vertical).join().includes(word);
}