283.Move Zeroes

📘 LeetCode 283: Move Zeroes

📌 Problem Overview

• Problem Number: 283
• Problem Name: Move Zeroes
• Difficulty: Easy
• Category: Two Pointers
• Runnable Source: Program.cs

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💡 Algorithmic Approach & Pattern

This problem is solved using the Two Pointers algorithmic pattern.

Key Insights & Invariants:

1. Identify the input constraints and edge conditions.
2. Structure the data flow to minimize unnecessary traversals and heap reallocations.
3. Validate corner cases (empty collections, single-element cases, duplicates, extremes).

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💻 Verified C# Implementation (.NET 9)

The solution is verified and executable via the companion project in src/283.Move-Zeroes/:

System.Console.WriteLine(MoveZeroes([1, 1, 2, 0]));
System.Console.WriteLine(MoveZeroes([0, 1, 0, 3, 12]));
System.Console.WriteLine(MoveZeroes([0, 0, 1, 1, 1, 2, 2, 3, 3, 4]));
int MoveZeroes(int[] nums)
{
    int i = -1;
    for (int j = 0; j < nums.Length; j++)
    {
        if (nums[j] != 0)
        {
            i++;
            int temp = nums[j];
            nums[j] = nums[i];
            nums[i] = temp;
        }
    }
    System.Console.WriteLine(string.Join(",", nums));
    return i;
}

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📊 Complexity Analysis

Metric	Complexity	Notes
Time Complexity	$\mathcal{O}(N)$ (or optimal for pattern)	Single or bounded passes over the input
Space Complexity	$\mathcal{O}(1)$ or $\mathcal{O}(N)$	Minimal auxiliary memory overhead

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🚨 Edge Cases & Interview Traps

• Empty / Null Input: Ensure null safety and guard clauses.
• Single Element: Confirm the algorithm terminates without out-of-bounds indexing.
• Duplicates & Boundaries: Check duplicate handling and extreme integer limits.