Regular Expression Matching: coding question

Problem

You get a string s and a pattern p. Return true if p matches all of s. Otherwise, return false.

The pattern can contain two special characters. The character . matches any one character. The character * matches zero or more copies of the character just before it.

Each other character in p matches only itself. The pattern must match the full string, not only a part of it.

Example 1

Input:: s = "aab", p = "a*b"
Output:: true
Explanation:: a* matches "aa", and b matches "b".

Example 2

Input:: s = "xyz", p = "x."
Output:: false
Explanation:: x. matches only two characters, but s has three characters.

Example 3

Input:: s = "mmmq", p = ".*q"
Output:: true
Explanation:: .* matches "mmm", and q matches "q".

Constraints

1 <= s.length <= 20
1 <= p.length <= 20
s has only lowercase English letters.
p has only lowercase English letters, `.` and `*`.
Each `*` in p has a letter or a `.` before it.

SysRound wrote this statement. A reference solution checks every example.

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Sources · 1 reference

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Amazon
Leetcode 10. Regular Expression Matching
Reported Jan 28, 2026 · 1 source report
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Source snapshot: Nov 12, 2026
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Microsoft
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STAFF
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Problem

You get a string s and a pattern p. Return true if p matches all of s. Otherwise, return false.

The pattern can contain two special characters. The character . matches any one character. The character * matches zero or more copies of the character just before it.

Each other character in p matches only itself. The pattern must match the full string, not only a part of it.

Example 1

Input:: s = "aab", p = "a*b"
Output:: true
Explanation:: a* matches "aa", and b matches "b".

Example 2

Input:: s = "xyz", p = "x."
Output:: false
Explanation:: x. matches only two characters, but s has three characters.

Example 3

Input:: s = "mmmq", p = ".*q"
Output:: true
Explanation:: .* matches "mmm", and q matches "q".

Constraints

1 <= s.length <= 20
1 <= p.length <= 20
s has only lowercase English letters.
p has only lowercase English letters, `.` and `*`.
Each `*` in p has a letter or a `.` before it.

SysRound wrote this statement. A reference solution checks every example.

Regular Expression Matching

Problem

Example 1

Example 2

Example 3

Constraints

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Regular Expression Matching

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