Today’s challenge was LeetCode – Zigzag Conversion, a great problem for practicing string manipulation, arrays, loops, and direction-based traversal in JavaScript.

The problem gives us a string and a number of rows. We need to arrange the characters in a zigzag pattern and then read the characters row by row to generate the final string.

For example:

PAYPALISHIRING

With numRows = 3, the characters are arranged like:

P   A   H   N
A P L S I I G
Y   I   R

Reading row by row gives:

PAHNAPLSIIGYIR

💡 Approach

The key idea is to maintain an array where each element represents a row.

We start from the first row and move downward. Once we reach the last row, we change direction and move upward. When we reach the first row again, we switch direction back to downward.

In JavaScript, this can be implemented efficiently using:

• Array() to create the required rows
• .fill('') to initialize them
• for...of to iterate through characters
• A currentRow variable to track the position
• A goingDown boolean to control the direction
• .join('') to combine all rows into the final answer

One important edge case is when the number of rows is greater than or equal to the string length. In that situation, the original string can simply be returned because no meaningful zigzag arrangement is possible.

🧠 What I Learned

This problem is a good reminder that many string problems become easier when we think about movement and state rather than trying to manipulate the entire string directly.

It also reinforces the importance of handling edge cases before running the main logic.

Successfully accepted with all test cases passed ✅

Continuing to solve problems, improve problem-solving skills, and write cleaner JavaScript code one challenge at a time. 💻🔥

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