Top Interview 150

The Longest Common Prefix problem is a classic string manipulation challenge that tests your ability to identify shared patterns among strings. Let’s break down

Output: "fl"

Alternative Solution: Vertical Scanning

Instead of comparing strings one by one, you can compare characters at each index across all strings.

var longestCommonPrefix = function(strs) {

    if (!strs.length) return "";



    for (let i = 0; i < strs[0].length; i++) {

        const char = strs[0][i];



        for (let j = 1; j < strs.length; j++) {

            if (i >= strs[j].length || strs[j][i] !== char) {

                return strs[0].slice(0, i);

            }

        }

    }



    return strs[0];

};

🔑 Complexity Analysis (Vertical Scanning)

• > Time Complexity: O(S), same as horizontal scanning.


• > Space Complexity: O(1).

✨ Pro Tips for Interviews

1. Clarify constraints: Confirm whether the array can be empty or contain strings of varying lengths.


2. Discuss edge cases:
   
   
   
   
   • Empty string array ([] → "").
   
   
   • Single string input (["single"] → "single").
   
   
   • Strings with no common prefix (["dog", "cat"] → "").
   
   
   
   


3. Explain your choice of approach: Highlight the difference between horizontal and vertical scanning.

📚 Learn More

Check out the full explanation and code walkthrough on my Dev.to post:

👉 Length of Last Word - JavaScript Solution

What’s your approach to solving this problem? Let’s discuss! 🚀

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