How do you solve Smallest String With A Given Numeric Value on LeetCode?

Smallest String With A Given Numeric Value (LeetCode #1663) 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: Building the string from the end allows for maximum flexibility in choosing characters.

What is the brute force solution for Smallest String With A Given Numeric Value?

The brute force approach for Smallest String With A Given Numeric Value is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach would involve generating all possible strings of length n and checking their numeric values until we find the one that matches k. This is inefficient as the number of combinations grows exponentially with n. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Smallest String With A Given Numeric Value?

Smallest String With A Given Numeric Value uses the following concepts: String, Greedy. The recommended patterns to study are: Greedy, Two Pointers.

What are the interview tips for Smallest String With A Given Numeric Value?

Always think about how to construct the solution step-by-step rather than brute-forcing through all possibilities. Clarify the constraints and edge cases before diving into coding. Practice explaining your thought process as you code to simulate the interview environment.

What are common mistakes when solving Smallest String With A Given Numeric Value?

Not considering the lexicographical order when constructing the string. Failing to correctly calculate the remaining value needed after initializing the string.

#1663

Smallest String With A Given Numeric Value

Medium

StringGreedyGreedyTwo Pointers

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

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

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Intuition

Time O(n)Space O(n)

Instead of generating all strings, we can construct the desired string directly. By starting from the end of the string and placing the highest possible character at each position, we ensure that we get the smallest lexicographical order.

⚙️

Algorithm

3 steps

1Step 1: Initialize a character array of size n filled with 'a'.
2Step 2: Calculate the remaining value needed by subtracting n from k.
3Step 3: Iterate from the end of the array to the beginning, placing the maximum possible character at each position until the remaining value is exhausted.

solution.py9 lines

1def smallestString(n, k):
2    result = ['a'] * n
3    k -= n
4    for i in range(n - 1, -1, -1):
5        if k > 0:
6            add = min(25, k)
7            result[i] = chr(ord('a') + add)
8            k -= add
9    return ''.join(result)

ℹ

Complexity note: The time complexity is O(n) because we only iterate through the string once to fill it, and the space complexity is O(n) due to the character array used to store the result.

1Building the string from the end allows for maximum flexibility in choosing characters.
2The greedy approach ensures that we always use the smallest possible characters first.

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