What is the solution to homelessness in the USA?

When I was given an assignment for my photography class to take a photo of something that makes me sad, I first thought of the old man that stands at the corner of my street every single day and, crouched in this cold weather under his thin layers of clothing, mumbles something not understandable which, if he had teeth, would probably sound like "help the old man with some money." Lately, I've been seeing more an more people begging in the streets, and every single time it crosses my mind - should I give them any money?

Somehow, I have always thought that there is a job for everyone. It may sound rude, but to me homeless (of course, this doesn't apply to all of them) are the people that don't do anything about making their lives easier. Many people begging in the streets are healthy and able to do some physical job. 

Well, at least this is how I saw the problem of homelessness in Serbia. I honestly do not know how it is here. The only thing I would do to change the situation would be giving the homeless opportunity to find a job. Any kind of job. But if they just prefer begging for money and sleeping in the streets, there is nothing the country could do to make their lives better.

Then again, there are those who are old, incapable of working and people with disabilities. For those my solution would be to build shelters, and provide home help, such as food and some clothes. But the only way this could work is if the people that are given the help were aware of it, and that way worked on keeping their shelters clean and acceptable to live in.