s2map | quick and dirty latlng visualizer | Map library

I have solved Two Strings problem in HackerRank

Here is the problem.

Given two strings, determine if they share a common substring. A substring may be as small as one character.

For example, the words "a", "and", "art" share the common substring. The words "be" and "cat" do not share a substring.

Function Description

Complete the function twoStrings in the editor below. It should return a string, either YES or NO based on whether the strings share a common substring.

twoStrings has the following parameter(s):

s1, s2: two strings to analyze .

Output Format

For each pair of strings, return YES or NO.

However, when extra-long strings are subjected, my code does not run within the time limit. Any suggestions to improve efficiency? I think I can improve substring finding with using the Stream API. But I'm not sure how to use it in this context. Could someone please help me to understand this better?