IT 討論區（48）最強工種，FG25K，你！敢唔敢成功？

python 25 行， time complexity:簡短

做Support都做到咁風騷
做programmer搵兩倍人工無人吼

想俾日本妹sm

人地有埋學校宿舍住
你班it9咪又係住公屋

[1,1]會炒

addBaseMinus2 []     []     0        = []
addBaseMinus2 [0]    [0]    0        = [0]
addBaseMinus2 []     ys     carry_in = addBaseMinus2 [0] ys carry_in
addBaseMinus2 xs     []     carry_in = addBaseMinus2 xs [0] carry_in
addBaseMinus2 (x:xs) (y:ys) carry_in = oneDigitSum : (addBaseMinus2 xs ys (-carryOut)) where
    (carryOut, oneDigitSum) = (x + y + carry_in) `divMod` 2

ceilOfHalf [] = []
ceilOfHalf xs = reverse . dropWhile (== 0) . reverse $ addBaseMinus2 xs (tail xs) 0

9行Haskell。應該係linear time，如果唔係。可以好容易用C/C++寫到係不過應該長D。如果output准有trailing zeros，可以唔洗reverse兩次同dropWhile。

sh-3.2$ ghci q.hs
GHCi, version 8.4.2: http://www.haskell.org/ghc/  :? for help
Loaded GHCi configuration from /Users/code4food/.ghci
[1 of 1] Compiling Main             ( q.hs, interpreted )
Ok, one module loaded.
*Main> ceilOfHalf []
[]
*Main> ceilOfHalf [1,0,0,1,1]
[1,0,1]
*Main> ceilOfHalf [1,0,0,1,1,1]
[1,0,1,0,1,1]
*Main> 

max唔可以食empty set

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<img src="/assets/faces/lm2/diu.gif" class="hkgmoji" /> <img src="/assets/faces/lm2/diu.gif" class="hkgmoji" />

做Support都做到咁風騷
做programmer搵兩倍人工無人吼<img src="/assets/faces/normal/frown.gif" class="hkgmoji" />

想俾日本妹sm<img src="/assets/faces/lm2/jable.gif" class="hkgmoji" /> <img src="/assets/faces/lm2/jable.gif" class="hkgmoji" /> <img src="/assets/faces/lm2/jable.gif" class="hkgmoji" />

黑C踩面

原來有炮房先係最重要

addBaseMinus2 []     []     0        = []
addBaseMinus2 [0]    [0]    0        = [0]
addBaseMinus2 []     ys     carry_in = addBaseMinus2 [0] ys carry_in
addBaseMinus2 xs     []     carry_in = addBaseMinus2 xs [0] carry_in
addBaseMinus2 (x:xs) (y:ys) carry_in = oneDigitSum : (addBaseMinus2 xs ys (-carryOut)) where
    (carryOut, oneDigitSum) = (x + y + carry_in) `divMod` 2

stripTrailingZeros []     = []
stripTrailingZeros (x:xs) = x : (reverse . dropWhile (== 0) $ reverse xs)

ceilOfHalf [] = []
ceilOfHalf xs = stripTrailingZeros $ addBaseMinus2 xs (tail xs) 0

多三行去處理list of zeroes，前面9行版 ceilOfHalf [1,1] 會出empty list。其實數值上無錯，因為empty list係對應0.

GHCi, version 8.4.2: http://www.haskell.org/ghc/  :? for help
Loaded GHCi configuration from /Users/code4food/.ghci
[1 of 1] Compiling Main             ( q.hs, interpreted )
Ok, one module loaded.
*Main> ceilOfHalf [1,0,0,1,1]
[1,0,1]
*Main> ceilOfHalf [1,0,0,1,1,1]
[1,0,1,0,1,1]
*Main> ceilOfHalf [1,1]
[0]
*Main> 

上面嗰啲係咪code嚟㗎好型呀
可唔可以教吓小妹

樓上咁多 code 聖

code4food

Actually，stripTrailingZeros處理output formatting嘅問題，咁addBaseMinus2其實可以再簡單D少一行。

addBaseMinus2 []     []     0        = [0]
addBaseMinus2 []     ys     carry_in = addBaseMinus2 [0] ys carry_in 
addBaseMinus2 xs     []     carry_in = addBaseMinus2 xs [0] carry_in 
addBaseMinus2 (x:xs) (y:ys) carry_in = oneDigitSum : (addBaseMinus2 xs ys (-carryOut)) where
    (carryOut, oneDigitSum) = (x + y + carry_in) `divMod` 2

stripTrailingZeros []     = []
stripTrailingZeros (x:xs) = x : (reverse . dropWhile (== 0) $ reverse xs)

ceilOfHalf [] = []
ceilOfHalf xs = stripTrailingZeros $ addBaseMinus2 xs (tail xs) 0

我都寫返兩句先

print(
  "!".join([
    "Hong Kong no IT" if x % 2 is 0
    else "一齊寫爛 code"
    for x in range(9999)
  ])
)

JS

Array.from(
  Array(9999).keys()
).map(
  x => x % 2 === 0 ?
  "Hong Kong no IT" :
  "一齊寫爛 code"
).join("!")

講番條題目：x = ceil(x/2) + floor(x/2) 所以 ceil(x/2) = x - floor(x/2)。而base -2 shift走最低digit其實就係 -floor(x/2)。AddBaseMinus2只係簡單嘅小學進位加法，不過因為係base -2所以我carryOut係要反轉正負，因為我2去除。

def solution(arr):
    for i in range(1, len(arr)):
        if arr[i] == 1:
            arr[i - 1] += 1
    for i in range(len(arr)-1):
        if arr[i] == 2:
            arr[i] = 0
            arr[i+1] -= 1
    while arr and arr[-1] == 0:
        arr.pop()
    return arr

python array.pop() remove trailing zeros都方便

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好clean, j死

Can you do it in O(1) memory? Imaging that you have a very long array (e.g. 1 billion digits) but your computer has very limited memory like 64K and a network interface.