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 t

numberOfBeams.js

/**
 * @param {string[]} bank
 * @return {number}
 */
// Function to calculate the total number of laser beams between security devices
var numberOfBeams = function(bank) {
    // Array to store the count of devices (i.e., '1's) in each non-empty row
    let arr = [];

    // Variable to accumulate the total number of beams
    let result = 0;

    // Iterate through each row in the bank
    for (let i = 0; i < bank.length; i++) {
        // Count the number of '1's (devices) in the current row
        let total = 0;

        for (let j = 0; j < bank[i].length; j++) {
            // Convert character to number and check if it's a device ('1')
            if (Number(bank[i][j]) === 1) {
                total += 1;
            }
        }

        // Only consider rows that contain at least one device
        if (total > 0) {
            arr.push(total);
        }
    }

    // Calculate beams between each pair of consecutive non-empty rows
    // The number of beams between two rows is the product of their device counts
    for (let i = 0; i < arr.length - 1; i++) {
        result += arr[i] * arr[i + 1];
    }

    // Return the total number of beams
    return result;
};