Add solution #2018

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,689 LeetCode solutions in JavaScript
+# 1,690 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1548,6 +1548,7 @@
 2014|[Longest Subsequence Repeated k Times](./solutions/2014-longest-subsequence-repeated-k-times.js)|Hard|
 2016|[Maximum Difference Between Increasing Elements](./solutions/2016-maximum-difference-between-increasing-elements.js)|Easy|
 2017|[Grid Game](./solutions/2017-grid-game.js)|Medium|
+2018|[Check if Word Can Be Placed In Crossword](./solutions/2018-check-if-word-can-be-placed-in-crossword.js)|Medium|
 2027|[Minimum Moves to Convert String](./solutions/2027-minimum-moves-to-convert-string.js)|Easy|
 2033|[Minimum Operations to Make a Uni-Value Grid](./solutions/2033-minimum-operations-to-make-a-uni-value-grid.js)|Medium|
 2037|[Minimum Number of Moves to Seat Everyone](./solutions/2037-minimum-number-of-moves-to-seat-everyone.js)|Easy|

solutions/2018-check-if-word-can-be-placed-in-crossword.js

@@ -0,0 +1,66 @@
+/**
+ * 2018. Check if Word Can Be Placed In Crossword
+ * https://leetcode.com/problems/check-if-word-can-be-placed-in-crossword/
+ * Difficulty: Medium
+ *
+ * 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 right
+ *   of 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 false otherwise.
+ */
+
+/**
+ * @param {character[][]} board
+ * @param {string} word
+ * @return {boolean}
+ */
+var placeWordInCrossword = function(board, word) {
+  const rows = board.length;
+  const cols = board[0].length;
+  const wordLen = word.length;
+
+  function canPlace(row, col, dr, dc) {
+    for (let i = 0; i < wordLen; i++) {
+      const r = row + i * dr;
+      const c = col + i * dc;
+      if (r < 0 || r >= rows || c < 0 || c >= cols || board[r][c] === '#') return false;
+      if (board[r][c] !== ' ' && board[r][c] !== word[i]) return false;
+    }
+
+    const beforeR = row - dr;
+    const beforeC = col - dc;
+    const afterR = row + wordLen * dr;
+    const afterC = col + wordLen * dc;
+
+    if ((beforeR >= 0 && beforeR < rows && beforeC >= 0
+        && beforeC < cols && board[beforeR][beforeC] !== '#')
+        || (afterR >= 0 && afterR < rows && afterC >= 0
+           && afterC < cols && board[afterR][afterC] !== '#')) {
+      return false;
+    }
+
+    return true;
+  }
+
+  for (let r = 0; r < rows; r++) {
+    for (let c = 0; c < cols; c++) {
+      if (canPlace(r, c, 0, 1) || canPlace(r, c, 0, -1)
+          || canPlace(r, c, 1, 0) || canPlace(r, c, -1, 0)) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+};