The Minimum Sum of Four Digit Number After Splitting Digits problem gives you a 4-digit integer. You must split its four digits into two 2-digit numbers such that their sum is minimized. This Minimum Sum of Four Digit Number After Splitting Digits coding problem is a simple greedy problem that tests digit sorting and strategic number construction.
Microsoft, Meta, and Amazon include this as a quick screening question to verify basic sorting and greedy reasoning. It's intended as a warm-up: can you recognize that the smallest sum comes from balancing the tens digits evenly? The math, sorting, and greedy interview pattern applies directly.
Sort the digits, then pair strategically. Sort the four digits in ascending order. To minimize the sum of two 2-digit numbers, assign the two smallest digits to the tens places and the two larger digits to the units places. Specifically: form numbers 10*d[0] + d[2] and 10*d[1] + d[3] (where d is the sorted digit array). Their sum is the minimum possible.
Number: 2932. Digits: [2, 9, 3, 2]. Sorted: [2, 2, 3, 9].
Alternative: 102 + 9 = 29 and 102 + 3 = 23 → same sum. Wrong approach: 102 + 2 = 22 and 103 + 9 = 39 → sum = 61 (worse).
Easy greedy problems reward rapid recognition of the optimal assignment rule. For "minimize sum of numbers built from digits," always think about placing the smallest digits in the highest-value positions (tens, hundreds, etc.) and spreading them evenly. After solving this, practice the generalization: constructing K numbers from N digits to minimize their sum — the same greedy principle applies at larger scales and appears in medium-difficulty interview questions.
| Title | Difficulty | Topics | LeetCode |
|---|---|---|---|
| Split With Minimum Sum | Easy | Solve | |
| Largest Perimeter Triangle | Easy | Solve | |
| Smallest Range II | Medium | Solve | |
| Append K Integers With Minimal Sum | Medium | Solve | |
| Maximum Difference by Remapping a Digit | Easy | Solve |
