DDSA Solutions

1844. Replace All Digits with Characters

EasyView on LeetCode
String
Time: O(n)
Space: O(n)

Problem Overview

Replace All Digits with Characters (Easy) asks you to solve a structured algorithmic task. This is a common String pattern in coding interviews. For each even-index letter, shift the following digit to produce the target char.

A full step-by-step explanation is being added. See the study guide for pattern-based practice.

Approach

For each even-index letter, shift the following digit to produce the target char.

Related patterns: String

1844.cs
C#
// Approach: For each even-index letter, shift the following digit to produce the target char.
// Time: O(n) Space: O(n)

public class Solution
{
    public string ReplaceDigits(string s)
    {
        char[] chars = s.ToCharArray();
        for (int i = 1; i < chars.Length; i += 2)
            chars[i] = (char)(chars[i] + chars[i - 1] - '0');

        return new string(chars);
    }
}
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