2125. Number of Laser Beams in a Bank

Hi Guys, Today is 3 January 2024 and below is the solution for problem of the day

So, the question we have is Number of Laser Beams in a Bank. 

In this we have to find total number of lasers. So just imagine it as we have to find number of lines connecting the dots.  so if there are 2 dots. we will have one line, if we have 3 dots we will get 3 lines, and so on...

Now relate the above provided example, let's relate this to our problem statement.

 

We have 4 walls, first wall has 3 lasers, second wall has 0 lasers, third wall got 2 lasers and last wall has 1 laser. So as i suggested we need to connect dots so make sure to only join adjacent dots. So lasers from 1 and 3 wall  will connect to each other (6 lasers) and wall 3 and 4 will connect to each other (2 lasers). So total of 8 lasers, which is the required output anyways.

class Solution:

def numberOfBeams(self, bank: List[str]) -> int:

val = 0 # Initialize a variable `val` to store the total number of beams

temp = 0 # Initialize a temporary variable `temp` to store the count of lasers 

in the previous row

# Iterate through each row (represented by `lasers`) in the `bank`

for lasers in bank:

count = 0 # Initialize a variable `count` to store the count of lasers in

 the current row

# Iterate through each character (laser) in the current row

for laser in lasers:

if laser == "1":

count += 1 # Increment `count` if the character is "1"

# Check if there are any lasers in the current row

if count:

val += (temp * count) # Add the product of `temp` and `count` to the

 total `val`

temp = count # Update `temp` with the count of lasers in the current 

row for the next iteration

return val # Return the total number of beams

 

Code Explanation:

Explanation:

1. The code defines a class named Solution.

2. Inside the class, there's a method named numberOfBeams that takes a list of strings (bank) as its input and returns an integer.

3. The method initializes two variables, val and temp, to keep track of the total number of beams and the count of lasers in the previous row, respectively.

4. It then iterates through each row (lasers) in the bank.

5. For each row, it counts the number of lasers (count) by iterating through each character in the row. If a character is "1", the count is incremented.

6. If there are any lasers in the current row (i.e., count is non-zero), it adds the product of temp and count to the total val. This is done to calculate the number of beams formed by connecting lasers in consecutive rows.

7. The temp variable is updated with the count of lasers in the current row for the next iteration.

8. Finally, the method returns the total number of beams (val).

In summary, the code calculates the total number of beams formed by connecting lasers in consecutive rows, where each row is represented by a string of "0" and "1" characters. The number of beams is determined by multiplying the count of lasers in the current row with the count of lasers in the previous row.

 

Performance - 

1. Time Complexity - O(N*M), N=number of row (length of bank array) and M = number of cells in each row (length of each value in bank array)

2. Space complexity - O(1)

 

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