Largest Number

medium

Arrange numbers to form the largest possible number

Largest Number

Key Insight

Compare by concatenation: "9"+"34"="934" vs "34"+"9"="349" → 9 comes first

Step 1Input Numbers
Convert to strings for comparison
3
0
30
1
34
2
5
3
9
4

Arrange [3, 30, 34, 5, 9] to form the largest number.

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Learn the Pattern

SortingUse sorting as a preprocessing step to simplify problems, or apply partition logic for in-place rearrangement. Many interview problems become trivial once the array is sorted.
Practice the Code

Step-by-Step Walkthrough: Largest Number

Compare by concatenation: "9"+"34"="934" vs "34"+"9"="349" → 9 comes first

  1. Input Numbers

    Arrange [3, 30, 34, 5, 9] to form the largest number.

  2. Compare 3 vs 30

    "330" vs "303". 330 > 303, so 3 comes before 30.

  3. Compare 5 vs 9

    "59" vs "95". 95 > 59, so 9 comes before 5.

  4. After Full Sort

    Custom comparator sorts: [9, 5, 34, 3, 30].

  5. Join Result

    Concatenate: "9" + "5" + "34" + "3" + "30" = "9534330".