What does it take to build an app from scratch? Time (a lot of it), and probably a little luck.

Leo Grand, a homeless man living on the streets of New York, was approached by 23-year-old programmer Patrick McConlogue and asked if he wanted $100, or to be taught coding javascript. Grand, who lost his home after being laid off from MetLife in 2011, chose to learn how to code. "I can go through $100 in a few days. In a week," Grand said. "But he told me I could have a laptop and learn how to do something and I figured it could turn into something more.

"It's not like I don't have the time to learn to do it."

So, every weekday before work, McConlogue came by the spot where Grand usually sets up, and taught him to code for an hour on a used Google Chromebook, using three coding manuals he purchased for Grand off of Amazon. Grand mentioned that he had a passion for climate change, and McConlogue encouraged that him to think of a way to make an impact through his app. And now, that app is here. It's called Trees for Cars, and is available on iTunes and Google Play for $.99. If you're a driver, the app lets you pick a meeting spot, and will notify you of other people in the area that are in need of a ride to that same spot. Trees for Cars will then calculate the amount of CO2 that was saved by the passengers hitching a ride.

There are some competing apps out there already, but none that I've seen that calculates CO2 saved. Pretty cool.

Oh, and all the proceeds go directly to Grand. 

[via Business Insider]