Add solution #2125

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,762 LeetCode solutions in JavaScript
+# 1,763 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1627,6 +1627,7 @@
 2121|[Intervals Between Identical Elements](./solutions/2121-intervals-between-identical-elements.js)|Medium|
 2122|[Recover the Original Array](./solutions/2122-recover-the-original-array.js)|Hard|
 2124|[Check if All A's Appears Before All B's](./solutions/2124-check-if-all-as-appears-before-all-bs.js)|Easy|
+2125|[Number of Laser Beams in a Bank](./solutions/2125-number-of-laser-beams-in-a-bank.js)|Medium|
 2127|[Maximum Employees to Be Invited to a Meeting](./solutions/2127-maximum-employees-to-be-invited-to-a-meeting.js)|Hard|
 2129|[Capitalize the Title](./solutions/2129-capitalize-the-title.js)|Easy|
 2130|[Maximum Twin Sum of a Linked List](./solutions/2130-maximum-twin-sum-of-a-linked-list.js)|Medium|

solutions/2125-number-of-laser-beams-in-a-bank.js

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+/**
+ * 2125. Number of Laser Beams in a Bank
+ * https://leetcode.com/problems/number-of-laser-beams-in-a-bank/
+ * Difficulty: Medium
+ *
+ * Anti-theft security devices are activated inside a bank. You are given a 0-indexed binary string
+ * array bank representing the floor plan of the bank, which is an m x n 2D matrix. bank[i]
+ * represents the ith row, consisting of '0's and '1's. '0' means the cell is empty, while'1'
+ * means the cell has a security device.
+ *
+ * There is one laser beam between any two security devices if both conditions are met:
+ * - The two devices are located on two different rows: r1 and r2, where r1 < r2.
+ * - For each row i where r1 < i < r2, there are no security devices in the ith row.
+ *
+ * Laser beams are independent, i.e., one beam does not interfere nor join with another.
+ *
+ * Return the total number of laser beams in the bank.
+ */
+
+/**
+ * @param {string[]} bank
+ * @return {number}
+ */
+var numberOfBeams = function(bank) {
+  let result = 0;
+  let prevDevices = 0;
+
+  for (const row of bank) {
+    let currentDevices = 0;
+    for (const cell of row) {
+      if (cell === '1') currentDevices++;
+    }
+    if (currentDevices > 0) {
+      result += prevDevices * currentDevices;
+      prevDevices = currentDevices;
+    }
+  }
+
+  return result;
+};