CodeReportSolutions

Code Report Solutions

Following are some simple solutions to videos found on YouTube. Idea is to make it easier for comparing and learning z^3 and other beautiful languages.

Number of Different Integers in a String

Video: https://www.youtube.com/watch?v=59vAjBS3yZM [APL Wins (vs C++, Java & Python)]

z^3 Solution

s="ad3343sadfsd343434df343443sff";
(s#/[^\d]+/)∪

Result: 3343 343434 343443

# splits string using the postfix regexp pattern. ∪ extracts unique from the results
12 Character z^3 Solution vs. 14 Character APL Solution

Final Value of Variable After Performing Operations

Video: https://www.youtube.com/watch?v=8Njxgy4itts [4 APL Solutions in 10 Minutes!]

z^3 Solution

m=["--x","x++","x++"].print();
[0]@(m!)

Gives answer:

x	[--x,x++,x++]
0	-1	-1	0

m! makes this to a function which is evaluated using [0]@. 0 forms a single input combinatorial argument.
[0..10]@(m!) can be used to loop through a set of initial values

Interesting that this solution has far less characters than APL solution, and  can be made even shorter.

Count Negative Numbers in a Sorted Matrix

Video: https://www.youtube.com/watch?v=pDbDtGn1PXk [LeetCode 176 Problem 1 - Count Negative Numbers in a Sorted Matrix]

z^3 Solution

x=[-2,-1,0;-1,1,3;-1,2,4];
(x⍌).findv(NEGATIVE)#

Gives answer 4

⍌ Flatten Array
.findv Gives result of function call NEGATIVE 
# Counts the result
Also note simpler z^3 Array Notation used to create the variable x (with , and ;). Usual Javascript array notations also work.

Check if a matrix is an X-Matrix (X like diagonals are filled)

Video: https://www.youtube.com/watch?v=8ynsN4nJxzU [APL vs BQN vs J vs Q vs NumPy vs Julia vs R - A comparison of seven different programming languages across a few different language criteria.]

z^3 Solution

m=[2 0 0 1; 0 3 1 0; 0 5 2 0; 4 0 0 2];
n=(m#)[0];
xm=|n| |+| |n|.reverse();
xm|==|(m.$("x!=0?1:0"!))

Gives answer true

m# gives length of array m. 
|n| gives n dimensional Identity Matrix, which is added using |+| to the .reverse() of same array.
|==| is used to compare this to the m, .$ is used to apply the function "x!=0?1:0"! to every element. "x!=0?1:0"! shows how a function can be created from a string with the ! operator.
Also note simpler z^3 Array Notation used to create the variable x (with , (when positive numbers alone are used, the comma is also optional) and ;). Usual Javascript array notations also work.