# String Cheatsheet

A string is a sequence of characters. Many tips that apply to Arrays also apply to Strings.

#### Time complexity[​](https://www.techinterviewhandbook.org/algorithms/string/#time-complexity "Direct link to Time complexity")

A Strings is an array of characters, so the time complexities of basic string operations will closely resemble that of array operations.

<table id="bkmrk-operation-big-o-acce"><thead><tr><th>Operation</th><th>Big-O</th></tr></thead><tbody><tr><td>Access</td><td>O(1)</td></tr><tr><td>Search</td><td>O(n)</td></tr><tr><td>Insert</td><td>O(n)</td></tr><tr><td>Remove</td><td>O(n)</td></tr></tbody></table>


#### Operations involving another String[​](https://www.techinterviewhandbook.org/algorithms/string/#operations-involving-another-string "Direct link to Operations involving another string")

Here we assume the other string is of length m.

<table id="bkmrk-operation-big-o-find"><thead><tr><th>Operation</th><th>Big-O</th></tr></thead><tbody><tr><td>Find substring</td><td>O(n.m)</td></tr><tr><td>Concatenating strings</td><td>O(n + m)</td></tr><tr><td>Slice</td><td>O(m)</td></tr><tr><td>Split (by token)</td><td>O(n + m)</td></tr><tr><td>Strip (remove leading and trailing whitespaces)</td><td>O(n)</td></tr></tbody></table>


#### Things to look out for during interviews[​](https://www.techinterviewhandbook.org/algorithms/string/#things-to-look-out-for-during-interviews "Direct link to Things to look out for during interviews")

- Ask about input character set and case sensitivity.

#### Corner cases[​](https://www.techinterviewhandbook.org/algorithms/string/#corner-cases "Direct link to Corner cases")

- Empty string
- String with 1 or 2 characters
- String with repeated characters
- Strings with only distinct character