2018. Check if Word Can Be Placed In Crossword

Description

You are given an m x n matrix board, representing the current state of a crossword puzzle. The crossword contains lowercase English letters (from solved words), ' ' to represent any empty cells, and '#' to represent any blocked cells.

A word can be placed horizontally (left to right or right to left) or vertically (top to bottom or bottom to top) in the board if:

• It does not occupy a cell containing the character '#'.
• The cell each letter is placed in must either be ' ' (empty) or match the letter already on the board.
• There must not be any empty cells ' ' or other lowercase letters directly left or rightof the word if the word was placed horizontally.
• There must not be any empty cells ' ' or other lowercase letters directly above or below the word if the word was placed vertically.

Given a string word, return true if word can be placed in board, or falseotherwise.

 

Example 1:

Input: board = [["#", " ", "#"], [" ", " ", "#"], ["#", "c", " "]], word = "abc"
Output: true
Explanation: The word "abc" can be placed as shown above (top to bottom).

Example 2:

Input: board = [[" ", "#", "a"], [" ", "#", "c"], [" ", "#", "a"]], word = "ac"
Output: false
Explanation: It is impossible to place the word because there will always be a space/letter above or below it.

Example 3:

Input: board = [["#", " ", "#"], [" ", " ", "#"], ["#", " ", "c"]], word = "ca"
Output: true
Explanation: The word "ca" can be placed as shown above (right to left). 

 

Constraints:

• m == board.length
• n == board[i].length
• 1 <= m * n <= 2 * 105
• board[i][j] will be ' ', '#', or a lowercase English letter.
• 1 <= word.length <= max(m, n)
• word will contain only lowercase English letters.

 

Solutions

Solution: Simulation

• Time complexity: O(mn)
• Space complexity: O(mn)

 

JavaScript

/**
 * @param {character[][]} board
 * @param {string} word
 * @return {boolean}
 */
const placeWordInCrossword = function (board, word) {
  const m = board.length;
  const n = board[0].length;
  const isCorner = cell => cell === '#' || cell === undefined;
  const isCanPlaced = (row, col, moveX, moveY) => {
    for (const element of word) {
      const letter = board[row]?.[col];

      if (letter !== element && letter !== ' ') return false;
      row += moveY;
      col += moveX;
    }
    return isCorner(board[row]?.[col]);
  };

  for (let row = 0; row < m; row++) {
    for (let col = 0; col < n; col++) {
      if (isCorner(board[row][col])) continue;
      const leftCell = board[row][col - 1];
      const rightCell = board[row][col + 1];
      const aboveCell = board[row - 1]?.[col];
      const bellowCell = board[row + 1]?.[col];

      if (isCorner(leftCell) && isCanPlaced(row, col, 1, 0)) return true;
      if (isCorner(rightCell) && isCanPlaced(row, col, -1, 0)) return true;
      if (isCorner(aboveCell) && isCanPlaced(row, col, 0, 1)) return true;
      if (isCorner(bellowCell) && isCanPlaced(row, col, 0, -1)) return true;
    }
  }
  return false;
};