easyString Basics

Rotate String

Determine whether rotating the first string left zero or more times can produce the second.

LeetCode ↗

Work through the cases

3 examples

Input notation

Two nonempty strings on separate lines.

Expected result

true or false.

Case 1

Input

abcde
cdeab

Expected output

true

Case 2

Input

abc
acb

Expected output

false

Case 3

Input

a
a

Expected output

true

These notes use simplified input/output notation. The linked platform defines the method signature and judge format.

FROM IDEA TO IMPLEMENTATION

Understand the approach.

Compare the documented approaches below. Brute force, better, and optimal versions appear where available; a direct exercise may need only one approach.

Is goal a rotation of s? Unequal lengths fail; otherwise goal is a substring of s+s.

class Solution {
    public boolean rotateString(String s, String goal) {
        return s.length() == goal.length() && (s + s).contains(goal);
    }
}

Reference code. Platform solutions may use supplied node types, imports, or collection libraries; foundational examples are complete programs.

Solutions adapted from Doocs / LeetCode contributors, licensed under CC BY-SA 4.0. Formatting changed; TypeScript versions converted to JavaScript. Supplemental implementations and approach notes added. Adapted solution material is available under the same license.