Add solution #1138

Author: JoshCrozier

README.md

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-# 1,147 LeetCode solutions in JavaScript
+# 1,148 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -894,6 +894,7 @@
 1130|[Minimum Cost Tree From Leaf Values](./solutions/1130-minimum-cost-tree-from-leaf-values.js)|Medium|
 1131|[Maximum of Absolute Value Expression](./solutions/1131-maximum-of-absolute-value-expression.js)|Medium|
 1137|[N-th Tribonacci Number](./solutions/1137-n-th-tribonacci-number.js)|Easy|
+1138|[Alphabet Board Path](./solutions/1138-alphabet-board-path.js)|Medium|
 1143|[Longest Common Subsequence](./solutions/1143-longest-common-subsequence.js)|Medium|
 1161|[Maximum Level Sum of a Binary Tree](./solutions/1161-maximum-level-sum-of-a-binary-tree.js)|Medium|
 1189|[Maximum Number of Balloons](./solutions/1189-maximum-number-of-balloons.js)|Easy|

solutions/1138-alphabet-board-path.js

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+/**
+ * 1138. Alphabet Board Path
+ * https://leetcode.com/problems/alphabet-board-path/
+ * Difficulty: Medium
+ *
+ * On an alphabet board, we start at position (0, 0), corresponding to character board[0][0].
+ *
+ * Here, board = ["abcde", "fghij", "klmno", "pqrst", "uvwxy", "z"], as shown in the diagram below.
+ *
+ * We may make the following moves:
+ * - 'U' moves our position up one row, if the position exists on the board;
+ * - 'D' moves our position down one row, if the position exists on the board;
+ * - 'L' moves our position left one column, if the position exists on the board;
+ * - 'R' moves our position right one column, if the position exists on the board;
+ * - '!' adds the character board[r][c] at our current position (r, c) to the answer.
+ *
+ * (Here, the only positions that exist on the board are positions with letters on them.)
+ *
+ * Return a sequence of moves that makes our answer equal to target in the minimum number of
+ * moves. You may return any path that does so.
+ */
+
+/**
+ * @param {string} target
+ * @return {string}
+ */
+var alphabetBoardPath = function(target) {
+  let path = '';
+  let row = 0;
+  let col = 0;
+
+  for (const char of target) {
+    const code = char.charCodeAt(0) - 97;
+    const targetRow = Math.floor(code / 5);
+    const targetCol = code % 5;
+
+    while (row > targetRow) path += 'U', row--;
+    while (col > targetCol) path += 'L', col--;
+    while (row < targetRow) path += 'D', row++;
+    while (col < targetCol) path += 'R', col++;
+
+    path += '!';
+  }
+
+  return path;
+};