HackerRank - Matrix Rotation - Code review - Series 2 of 10+

Dec. 6, 2016

Problem statement:
https://www.hackerrank.com/challenges/matrix-rotation-algo

Study code:
https://gist.github.com/jianminchen/fd5e7e7e4a031971e56dc30a949e5421

Code review:

Julia took 20 minutes to go over the code, and then understood the code.

A few changes:
 /*
     * Code review:
     *  a -> matrix - function argument
     *  amount -> steps
     *  k -> step, for loop statement
     *  buffer -> prev
     *  buffer1 -> cur
     *
     * Good ideas to study:
     * 1. height, width variables are declared
     * 2. go through the ring: start from second row, first column, anti-clockwise, one-by-one
     *    if/else if statement - 4 lines - very easy to follow
     */
Study do while loop, and also if/else if to do anti-clockwise rotation starting from left-upper corner.

https://gist.github.com/jianminchen/91719129b81eefb19f662615b4e3ab95

Great tip Julia likes to share:
Instead of using four for loop to go through the ring, use if/else if to make it one loop - using do/ while. Easy to write, only 4 lines.

Compare two solutions:

Current one in the blog: smart choice, using one loop - do while - 4 if/else  (Excellent!)
This solution can be memorized, and cut the time to write in less than 10 minutes. 
https://gist.github.com/jianminchen/91719129b81eefb19f662615b4e3ab95

Previous one:   kind of verbose, dumb, 4 for loops.
https://gist.github.com/jianminchen/e943a9e7b86d24e9f36c04f1f3502941