Easy data structure and algorithm practice puzzle.
Given strings s and t, return true if you can find the letters of s inside t, in order, possibly with other letters in between. So "abc" is in "ahbgdc". Use two pointers. Walk through t, and every time its letter matches the next letter of s, move to the next letter of s. If you match all of s, it's true. An empty s always is.
Solve it three ways: snap the jigsaw pieces together, fill in the blanks, or type it from scratch against the tests. This one is free.
Every line of the solution comes with a note explaining why it is there, and a step by step replay shows the code running. At level 3, where you type it yourself, you can ask for an AI mock interview on this problem that ends with a hiring manager's scorecard.
Then grow it into a real project with the Software Engineer button: this puzzle becomes the Document Reconciler, a pipeline you can run and download. See every Software Engineer project.
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