# Tag Info

Accepted

### Index of a multidimensional array

APL, 1 byte Test it on TryAPL.

### N-dimensional N^N array filled with N

Python, 32 bytes lambda n:eval('['*n+'n'+']*n'*n) Try it online! Makes a string like "[[[n]*n]*n]*n" with ...
Accepted

### Cheating a multiple choice test

Jelly, 7 6 bytes _/ị“ḃ» Typing on phone. Will add description. (1,0) goes to A, ...

### Be the First 1 (leave only the first Truthy)

Python 2, 35 bytes while 1:b=input();print b;True&=b<1 Try it online! Input and output are lines of True/False. Based on Dennis's solution. Redefines the ...
Accepted

### Lossy Sorting (Implement Dropsort)

APL, 9 bytes ⊢(/⍨)⊢=⌈\ This is a monadic function train with diagram: ┌─┼───┐ ⊢ ⍨ ┌─┼─┐ ┌─┘ ⊢ = \ / ┌─┘ ⌈ The ...

### Moving modest minimum

Python 2, 41 bytes lambda l:[sorted(l)[x==min(l)]for x in l] Try it online! For each element x we check whether ...
Accepted

### Flatten the Array!

K, 3 bytes ,// This is a fairly common idiom. "Join over converge". try it here with oK. How it works: Join (,) fuses ...
Accepted

### Count trailing truths

Dyalog APL, 6 2 bytes ⊥⍨ Test it on TryAPL. How it works ⊥ (uptack, dyadic: decode) performs base conversion. If the left operand is a vector, it performs ...

### Remove surrounding zeroes of a 2d array

Wolfram Language (Mathematica), 42 bytes #&@@CellularAutomaton[{,{},0{,}},{#,0},0]& Try it online! Cellular automata are indeed the answer to life, the ...

### Output a string's cumulative slope

Python, 29 bytes lambda s:ord(s[-1])-ord(s) The sum of the differences forms a telescopic series, so most summands cancel out and (s1 - s0) + (s2 - s1) + &...

### Flatten the Array!

JavaScript (ES6), 35 bytes Inspired by @user81655's answer: f=a=>a.map?[].concat(...a.map(f)):a
Accepted

### Is it true? Ask Jelly!

Jelly, 3 bytes ṭFẠ F flattens the input list. tacks on the original input list as an ...

### Xorting an array

Pyth, 40 36 31 30 bytes Ju.|G^2slHxMf>FT.:Q2Z|tSIxRJQJ Try it online: Demonstration or Test Suite Each of the big test-cases finishes in a couple of seconds. ...
Accepted

### Be the First 1 (leave only the first Truthy)

APL, 2 bytes <\ Evaluates to the function "scan using less-than". Try it online! Explanation In APL, the operator \ (...

### Covering a Skyline with brush strokes

JavaScript (Node.js), 38 bytes a=>a.map(v=>(n+=v>p&&v-p,p=v),p=n=0)|n Try it online! Simply a greedy algorithm which scan from left to right, ...

### Surrounded Countries

Pyth, 7 bytes n{Q_{_Q Run the code on test cases. ...

### Remove every N-th N

awk, 10 bytes Input is expected on STDIN, one number per line. ++a[$1]%$1 Explanation Keeps a counter for each number in an associative array, prints only if ...

### N-dimensional N^N array filled with N

J, 4 bytes \$~#~ Try it online! Explanation ...

### Execute a Superb Shuffle™

Ruby, 31 bytes ->x{(0..53).map{|r|x[r*17%54]}} Try it online! Explanation: I'm picking one card, then skipping over the next 16 and start from the first card ...

### Turn an integer n into a list containing it n times

Jelly, 1 byte x Try it online! Note that this is not the “repeat n n times” built-in — ...

### Sum the array times n, except the last

J, 3 bytes That was fun to find. &+/ Try it online! How it works 10 (&+/) 3 1 4 1 5 will bind ...

### Halve the falses

Retina, 4 bytes 00 0 Try it online!
Accepted

### Find the longest word in an array

Imperative Tampio, 168 bytes ...

### Consolidate an Array

Pyth, 3 bytes !DQ Explanation: Q Input !D Sort by logical NOT Try it here.
Accepted

### Zigzagify a Matrix

J, 31 30 14 12 11 bytes [:;<@|.`</. Ych. Too big. Takes a matrix as input. Explanation J has an advantage here. There's a command called oblique (...

### Detect heat waves

C (gcc), 88 75 73 bytes Saved two bytes thanks to ceilingcat. h,e,a;t(int*_){for(h=e=a=0;*_;h+=e>4&a>2)e=*_<25?a=0:++e,a+=*_++>29;e=h;} Try it ...

### Covering a Skyline with brush strokes

05AB1E,  8 7  5 bytes Saved 2 bytes thanks to @Adnan 0š¥þO Try it online! How? This is using the algorithm that was first found by @tsh. If you like this answer, ...

### Invert a boolean array

05AB1E, 1 byte Code: _ Explanation: _ # Logical not Try it online!