Question

Technologies:

javascript

Tolerim

an hour ago

Rephrase: Locate a two-dimensional array within another two-dimensional array.

My objective is to search for a 2D array inside another 2D array, as shown in the code below:

let board = [
  [ '0', '0', '0', '0' ],
  [ '1', '1', '1', '1' ],
  [ '2', '3', '3', '4' ]
];
let toFind = [ [ '1', '1' ], [ '4' ] ];

When found, the function should return the index of the located array. For the given code, the expected result would be [1,2]

In order to achieve this, I've created two functions. The first function, findIndex, traverses through the board array, attempting to locate the first element of toFind array. Upon finding it, the second function, checkMatch, compares each subsequent element to see if a match is found.

const findIndex = (toFind, board) => {
  let results = [];
  for (let i = 0; i < board.length; i++) {
    for (let j = 0; j < board[i].length; j++) {
      if (board[i][j] == toFind[0][0]) {
        if (checkMatch(board, toFind, i, j)) {
          console.log("Match Found");
          results.push([i, j]);
          return results;
        }
      }
    }
  }
  console.log("Not found");
};
const checkMatch = (board, toFind, row, col) => {
  let match = true;
  for (let i = row; i < row + toFind.length; i++) {
    for (let j = col; j < col + toFind[i - row].length; j++) {
      if (toFind[i - row][j - col] != board[i][j]) {
        match = false;
      }
    }
  }
  console.log(match);
  return match;
};

Unfortunately, the findIndex function isn't working as efficiently as needed, producing the wrong result [1,0]. There seems to be an issue with my checkMatch function, but I'm uncertain about how to correct it.

Answers(1)

Accepted Answer

The issue with your checkMatch function is that the inner loop should be iterating over the columns of toFind[i], not board[i]. Here's the corrected implementation:

const checkMatch = (board, toFind, row, col) => {
  let match = true;
  for (let i = row; i < row + toFind.length; i++) {
    for (let j = col; j < col + toFind[i - row].length; j++) {
      if (toFind[i - row][j - col] !== board[i][j]) {
        match = false;
      }
    }
  }
  console.log(match)
  return match;
};

With this correction, your findIndex function should work correctly and return [1,2] for the example input.