A certain street has between 50 and 500 houses in a row, numbered 1, 2, 3, 4, … consecutively. There is a certain house on the street such that the sum of all the house numbers to the left side of it is equal to the sum of all the house numbers to its right. Find the number of this house.
— source
If there are k houses and we are at house n, we can relate k and n using the triangular numbers as follows:
| ?- balanced_parens(Q). | |
| Q = "" ; | |
| Q = "()" ; | |
| Q = "(())" ; | |
| Q = "((()))" ; | |
| Q = "(()())" ; | |
| Q = "(((())))" ; | |
| Q = "((()()))" ; | |
| Q = "(()(()))" ; | |
| Q = "(()()())" ; |
| type point = int * int | |
| type child = | |
| | Line of point * point | |
| | Arc of point * point * bool | |
| type svg = { width : int | |
| ; height : int | |
| ; stroke : int | |
| ; zoom : float |
| module IntPairs = Set.Make ( | |
| struct | |
| type t = int * int | |
| let compare = compare | |
| end | |
| ) | |
| let () = | |
| let ips = IntPairs.of_list [(1, 1); (1, 2); (2, 1); (1, 2)] | |
| in | |
| IntPairs.iter |
| #!/bin/sh | |
| mkdir App.iconset | |
| sips -z 16 16 Icon1024.png --out App.iconset/icon_16x16.png | |
| sips -z 32 32 Icon1024.png --out App.iconset/icon_16x16@2x.png | |
| sips -z 32 32 Icon1024.png --out App.iconset/icon_32x32.png | |
| sips -z 64 64 Icon1024.png --out App.iconset/icon_32x32@2x.png | |
| sips -z 128 128 Icon1024.png --out App.iconset/icon_128x128.png | |
| sips -z 256 256 Icon1024.png --out App.iconset/icon_128x128@2x.png | |
| sips -z 256 256 Icon1024.png --out App.iconset/icon_256x256.png |
| #lang racket | |
| (define (assert-equal a b) | |
| (if (equal? a b) | |
| (void) | |
| (error "Assertion failure got" a "expected" b))) | |
| (define-syntax-rule (s-cons a b) (lambda () (cons a b))) | |
| (define (s-car stream) (car (stream))) | |
| (define (s-cdr stream) (cdr (stream))) |
| const assert = require("assert"); | |
| // Utilities for building and using linked lists | |
| const cons = (a, b) => [a, b]; | |
| const car = ([a, b]) => a; | |
| const cdr = ([a, b]) => b; | |
| function toArray(ls, acc = []) { | |
| if (ls.length === 0) { | |
| return acc; | |
| } |
| (λ (f) | |
| ((λ (x) (f (x x))) | |
| (λ (x) (f (x x))))) |
| {"gameLink":"www.flickgame.org","canvasses":[[4430,"0",11,"5",147,"0",15,"5",135,"0",4,"5",5,"0",17,"5",126,"0",6,"5",1,"0",6,"5",3,"0",19,"5",124,"0",14,"5",3,"0",19,"5",94,"0",8,"5",21,"0",16,"5",1,"0",7,"5",7,"0",6,"5",68,"0",8,"5",17,"0",10,"5",20,"0",23,"5",9,"0",5,"5",65,"0",12,"5",2,"0",6,"5",7,"0",13,"5",16,"0",24,"5",10,"0",5,"5",64,"0",13,"5",1,"0",8,"5",5,"0",15,"5",14,"0",24,"5",9,"0",7,"5",63,"0",24,"5",3,"0",17,"5",12,"0",41,"5",63,"0",25,"5",2,"0",6,"5",4,"0",8,"5",11,"0",41,"5",63,"0",7,"5",3,"0",15,"5",1,"0",6,"5",6,"0",7,"5",10,"0",8,"5",1,"0",32,"5",64,"0",5,"5",5,"0",9,"5",1,"0",5,"5",1,"0",6,"5",5,"0",8,"5",10,"0",8,"5",1,"0",31,"5",65,"0",5,"5",5,"0",9,"5",1,"0",25,"5",10,"0",7,"5",2,"0",15,"5",1,"0",12,"5",67,"0",6,"5",5,"0",8,"5",2,"0",24,"5",11,"0",7,"5",2,"0",15,"5",80,"0",6,"5",5,"0",7,"5",3,"0",23,"5",12,"0",6,"5",3,"0",6,"5",1,"0",8,"5",80,"0",6,"5",5,"0",7,"5",3,"0",21,"5",14,"0",6,"5",3,"0",6,"5",1,"0",8,"5",80,"0",5,"5",6,"0",6,"5",4,"0",19,"5",16,"0",6,"5",3,"0",5,"5",2,"0",9, |
| function shorthand() { | |
| echo "${PWD/$HOME/~}" | tr "/" "\n" | cut -c 1 | tr "\n" "/" | rev | cut -c2- | rev | |
| } | |
| export PROMPT='%{$fg[cyan]%}$(shorthand)%{$reset_color%} $ ' |
