L2: Triple X

L2: Triple XCodewars

Approach

solve the problem

1. if x exist

   1. return 'x' index === 'xxx' index

2. if x doesn't exist return false

In mordern JS optional chaining is good option

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining

time complexity

1. if x exist (n)

   1. return 'x' index === 'xxx' index (2n)

2. if x doesn't exist return false

O = n

space complexity

O = n

Solution

JavaScript

// for older ES version
const tripleX = (str) => str.match('x') ? str.indexOf('x') === str.indexOf('xxx') : false;

// optional chaining
const tripleX = (str) => str.match('x')?.index === str.match('xxx')?.index;