Lecture 82 :-  Zig-Zag Conversion

The Zig-Zag Conversion is a text transformation problem where you are given a string and a number of rows, and you need to convert the string into a zig-zag pattern with the given number of rows. You can then read the transformed string row by row to obtain the final result.

Here's a Python function to perform the Zig-Zag Conversion:

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def zigzag_conversion(s, num_rows):    if num_rows == 1 or len(s) <= num_rows:        return s    result = [''] * num_rows    row, step = 0, 1    for char in s:        result[row] += char        if row == 0:            step = 1        elif row == num_rows - 1:            step = -1        row += step    return ''.join(result) # Example usage: input_str = "PAYPALISHIRING" num_rows = 3 output_str = zigzag_conversion(input_str, num_rows) print(output_str)

Output:

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"PAHNAPLSIIGYIR"

In this example, the function zigzag_conversion takes the input string s and the number of rows num_rows. It initializes an array of strings called result, where each element corresponds to a row in the Zig-Zag pattern. It then iterates through the characters of the input string and appends each character to the appropriate row in the result array.

The step variable controls the direction of movement while traversing the Zig-Zag pattern. When row is at the top or bottom row, the step is reversed to change direction.

Finally, the function joins the rows of the result array to create the final Zig-Zag converted string and returns it.

Note that if num_rows is equal to 1 or the length of the input string is less than or equal to num_rows, the function returns the original string as the Zig-Zag pattern with a single row is the same as the original string.