Compare Strings With Deletions
Compare Strings With Deletions
You are given two strings, s and t. Each string consists of lowercase English letters and the special character #.
The character # acts as a backspace: it deletes the closest non-deleted character immediately preceding it. If there is no non-deleted character before a #, then the # has no effect.
Your task is to determine if the two strings are equal after all such deletions are applied. Return true if they are equal, false otherwise.
Constraint: You must implement the comparison using O(1) auxiliary space. This means you cannot use additional data structures (like stacks or new strings) whose size scales with the input strings.
Examples:
Example 1:
Input: s = "ab#c", t = "ad#c"
Output: true
Explanation: Both strings become "ac".
Example 2:
Input: s = "a#c", t = "b"
Output: false
Explanation: The first string becomes "c", while the second becomes "b".
AI interview prep
Core dilemma
The central engineering conflict is how to simulate the string processing and comparison in real-time, character by character, without explicitly building the final strings, given the strict O(1) auxiliary space constraint. This requires careful pointer management and state tracking.
2 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
Compare Strings With Deletions
Compare Strings With Deletions
You are given two strings, s and t. Each string consists of lowercase English letters and the special character #.
The character # acts as a backspace: it deletes the closest non-deleted character immediately preceding it. If there is no non-deleted character before a #, then the # has no effect.
Your task is to determine if the two strings are equal after all such deletions are applied. Return true if they are equal, false otherwise.
Constraint: You must implement the comparison using O(1) auxiliary space. This means you cannot use additional data structures (like stacks or new strings) whose size scales with the input strings.
Examples:
Example 1:
Input: s = "ab#c", t = "ad#c"
Output: true
Explanation: Both strings become "ac".
Example 2:
Input: s = "a#c", t = "b"
Output: false
Explanation: The first string becomes "c", while the second becomes "b".