DZone MVB (Most Valuable Blogger)

dzone-mvb
Today, I’m really glad and honored to be selected as a DZone MVB (Most Valuable Blogger). DZone’s MVB program brings together a group of highly talented bloggers, authors, and technologists actively writing about topics of interest to the developer community. These people are recognized in the industry for their contributions and deep technical knowledge on subjects ranging from software design and architecture to programming on a range of platforms including Java, .NET, Ruby and others.

One of my main passion areas is generally speaking, writing, and sharing my experience and ideas with people. This is why I find writing books and blogging an interesting activity. I think writing (and speaking) is a great way to communicate and exchange our ideas (as a part of the WW community) with each others, and it is a wonderful way to enhance our experiences.
Screen Shot 2015-07-09 at 12.00.33 AM
When I began writing, My main aim was (and still) sharing my experience with the WW community in order to help people rapidly resolving problems that are similar to the problems that I face during my daily job, and also in order to learn from the community if they have better solutions.

I hope that, if you do not have your own technical blog yet, to start creating your own one and share your technical experience because it will be definitely useful to at least someone in somewhere in this world.

[JavaScript Quiz #15] All possible compositions of a number

Today’s JavaScript quiz is about finding all the possible compositions of a number. For example if we have a number 4, we would like to find all the possible compositions that sums up to 4 as follows.

1111
112
121
13
211
22
31
4

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In order to develop this utility, it is important to understand its nature. For a number n, it has the following possible compositions:
n (for a composition length of 1)
1 n-1 (for a composition length of 2)
1 1 n-2 (for a composition of length 3)

1 1 1 … 1 (for a composition of length n)

This can be handled using recursive function as follows.

function compositions(n, temp, output) {
    var i, newTemp;
    
    if (n == 0) {
        output.push(temp);
    } else {
        for (i = 1; i <= n; ++i) {
            newTemp = temp + i;
            
            compositions(n - i, newTemp, output);
        }
    }
}

As shown, the base is if n is equal to 0 then we add the temp string (which is initialized to "") to the output list, else we subtract i from n and adds i to the temp string. The following function getAllCompositions calls compositions with the initial values.

function getAllCompositions(n) {
    var out = [];
    
    compositions(n, "", out);
    
    return out;
}

Finally, we can test getAllCompositions as follows.

// Test ...
var num = 4;
var out = getAllCompositions(num), i;

console.log("Compositions number for (" + num + ") = " + out.length);
for (i = 0; i < out.length; ++i) {
	console.log(out[i]);
}

The output will be:

Compositions number for (4) = 8
    
1111 
112 
121  
13 
211  
22  
31  
4

If you have a better solution, feel free to put in the comments below. The current solution complexity is n!.