Add solution #1640

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,441 LeetCode solutions in JavaScript
+# 1,442 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1264,6 +1264,7 @@
 1637|[Widest Vertical Area Between Two Points Containing No Points](./solutions/1637-widest-vertical-area-between-two-points-containing-no-points.js)|Easy|
 1638|[Count Substrings That Differ by One Character](./solutions/1638-count-substrings-that-differ-by-one-character.js)|Medium|
 1639|[Number of Ways to Form a Target String Given a Dictionary](./solutions/1639-number-of-ways-to-form-a-target-string-given-a-dictionary.js)|Hard|
+1640|[Check Array Formation Through Concatenation](./solutions/1640-check-array-formation-through-concatenation.js)|Easy|
 1657|[Determine if Two Strings Are Close](./solutions/1657-determine-if-two-strings-are-close.js)|Medium|
 1668|[Maximum Repeating Substring](./solutions/1668-maximum-repeating-substring.js)|Easy|
 1669|[Merge In Between Linked Lists](./solutions/1669-merge-in-between-linked-lists.js)|Medium|

solutions/1640-check-array-formation-through-concatenation.js

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+/**
+ * 1640. Check Array Formation Through Concatenation
+ * https://leetcode.com/problems/check-array-formation-through-concatenation/
+ * Difficulty: Easy
+ *
+ * You are given an array of distinct integers arr and an array of integer arrays pieces,
+ * where the integers in pieces are distinct. Your goal is to form arr by concatenating
+ * the arrays in pieces in any order. However, you are not allowed to reorder the integers
+ * in each array pieces[i].
+ *
+ * Return true if it is possible to form the array arr from pieces. Otherwise, return false.
+ */
+
+/**
+ * @param {number[]} arr
+ * @param {number[][]} pieces
+ * @return {boolean}
+ */
+var canFormArray = function(arr, pieces) {
+  const numberToPiece = new Map();
+  for (const piece of pieces) {
+    numberToPiece.set(piece[0], piece);
+  }
+
+  let index = 0;
+  while (index < arr.length) {
+    const currentNumber = arr[index];
+    if (!numberToPiece.has(currentNumber)) {
+      return false;
+    }
+    const piece = numberToPiece.get(currentNumber);
+    for (const num of piece) {
+      if (arr[index] !== num) {
+        return false;
+      }
+      index++;
+    }
+  }
+
+  return true;
+};