How do you solve Maximize Sum of Squares of Digits on LeetCode?

Maximize Sum of Squares of Digits (LeetCode #3723) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(n) space complexity. Key insight: Maximize leftmost digits for higher scores

What is the time complexity of Maximize Sum of Squares of Digits?

The optimal solution for Maximize Sum of Squares of Digits runs in O(n) time and uses O(n) space. The algorithm runs in linear time as we iterate through the digits once.

What is the brute force solution for Maximize Sum of Squares of Digits?

The brute force approach for Maximize Sum of Squares of Digits is Brute Force, with O(n²) time complexity and O(1) space complexity. Generate all possible numbers with 'num' digits and check their digit sums. This is inefficient as it explores all combinations. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Maximize Sum of Squares of Digits?

Maximize Sum of Squares of Digits uses the following concepts: Math, Greedy. The recommended patterns to study are: Greedy, Array.

What are the interview tips for Maximize Sum of Squares of Digits?

Explain your thought process clearly Discuss edge cases upfront Practice similar greedy problems

What are common mistakes when solving Maximize Sum of Squares of Digits?

Overfilling digits beyond 'sum' Not accounting for leading zeros

#3723

Maximize Sum of Squares of Digits

Medium

MathGreedyGreedyArray

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(n)

💡

Intuition

Time O(n)Space O(n)

Use a greedy approach to fill the digits from left to right with the highest possible values (9s) while ensuring the total digit sum equals 'sum'.

⚙️

Algorithm

3 steps

1Step 1: Initialize an array of size 'num' with zeros.
2Step 2: Fill the array from left to right with 9s until the remaining sum is less than 9.
3Step 3: Place the remaining sum in the next position and convert the array to a string.

solution.py12 lines

1def maxSumOfSquares(num, sum):
2    if sum > 9 * num or sum == 0 and num > 1:
3        return ''
4    digits = [0] * num
5    for i in range(num):
6        if sum > 9:
7            digits[i] = 9
8            sum -= 9
9        else:
10            digits[i] = sum
11            break
12    return ''.join(map(str, digits))

ℹ

Complexity note: The algorithm runs in linear time as we iterate through the digits once.

1Maximize leftmost digits for higher scores
2Sum of digits must equal 'sum'

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.