Java for Beginners 4 – Working with Java Loop Statements

Java recognizes three types of loops, namely ‘for,’ ‘while’ and ‘do-while’ loops that all accomplish the similar goals of iterating the block of code until a certain condition is met. The following article explores the differences between each of the loop variants and demonstrates the situations when choosing one type of loop over the other can be a benefit. There are many examples of using all three types of loops, but I’ve selected the general form and the infinite loop to illustrate the primary differences.

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Polyomino Combinatorics: How to count distinct n- letter long array permutations

Let’s say we have 3 arrays of following tetromino letters: J, L, O. Tetromino J is a 4 member long array (J[0],J[1],J[2],J[3]), signifying the number of positions J block can take. L tetromino is also a 4 member long array and O is a square tetromino that has only one position (1 member long array). How do we calculate the total number of all unique n-letter long permutations, without programmatically permuting through them? [Read more…]