Problem: Remove Duplicate Letters

Medium

30 min

Understand how to use stacks to remove duplicate letters from a string while ensuring the final result is lexicographically smallest. This lesson guides you through problem constraints and solution strategies for efficient string manipulation commonly tested in coding interviews.

Statement

You are given a string, s, consisting only of lowercase English letters. Your task is to remove duplicate letters so that:

Each letter appears only once in the resulting string.
The resulting string is the smallest in lexicographical order among all possible results that satisfy the above condition.

Return the final string.

A string, a, is considered lexicographically smaller than string b if:
In the first position where they differ, the character in a appears earlier in the alphabet than in b.
If a is a prefix of b, then a is considered smaller.

Constraints:

$1 \leq$ s.length $\leq 10^3$
s consists of lowercase English letters.

Problem: Remove Duplicate Letters

Medium

30 min

Statement

You are given a string, s, consisting only of lowercase English letters. Your task is to remove duplicate letters so that:

Each letter appears only once in the resulting string.
The resulting string is the smallest in lexicographical order among all possible results that satisfy the above condition.

Return the final string.

A string, a, is considered lexicographically smaller than string b if:
In the first position where they differ, the character in a appears earlier in the alphabet than in b.
If a is a prefix of b, then a is considered smaller.

Constraints:

$1 \leq$ s.length $\leq 10^3$
s consists of lowercase English letters.

Problem: Remove Duplicate Letters

Statement

Examples

Understand the problem

Figure it out!

Try it yourself

Problem: Remove Duplicate Letters

Statement

Examples

Understand the problem

Figure it out!

Try it yourself