【codewar-4kyu】Snail 待学习
##题目描述
Description:
Snail Sort
Given an n x n array, return the array elements arranged from outermost elements to the middle element, traveling clockwise.
array = [[1,2,3],
[4,5,6],
[7,8,9]]
snail(array) #=> [1,2,3,6,9,8,7,4,5]For better understanding, please follow the numbers of the next array consecutively:
array = [[1,2,3],
[8,9,4],
[7,6,5]]
snail(array) #=> [1,2,3,4,5,6,7,8,9]
This image will illustrate things more clearly:
NOTE: The idea is not sort the elements from the lowest value to the highest; the idea is to traverse the 2-d array in a clockwise snailshell pattern.
NOTE 2: The 0x0 (empty matrix) is represented as [[]]我好像最后还是没考虑空矩阵的处理。。。啊啊啊啊，路漫漫啊
##思路分析
突然给我来了道4kyu....写了半天写了一长串，结果答案里别人一句就写完了。。。一句。。我的内心是崩溃的
##代码解析
Python，先贴别人的以便学习,第一个方案真是巧妙啊，服。每次递归取第一行，通过zip(*array[1:]）将剩下的行列转换,通过[::-1]倒序输出为snail的argument，就又可以取第一行了！
方案3思想和方案1一致，但是表达得直观，更适合我等菜鸟学习。
1 #方案1 2 def snail(array): 3 return list(array[0]) + snail(zip(*array[1:])[::-1]) if array else []
1 #方案2 2 def snail(array): 3 ret = [] 4 if array and array[0]: 5 size = len(array) 6 for n in xrange((size + 1) // 2): 7 for x in xrange(n, size - n): 8 ret.append(array[n][x]) 9 for y in xrange(1 + n, size - n): 10 ret.append(array[y][-1 - n]) 11 for x in xrange(2 + n, size - n + 1): 12 ret.append(array[-1 - n][-x]) 13 for y in xrange(2 + n, size - n): 14 ret.append(array[-y][n]) 15 return ret
#方案3 def snail(array): a = [] while array: a.extend(list(array.pop(0))) array = zip(*array) array.reverse() return a
方案3注意 extend，非 append。extend 的参数是 list.
下面是我自己的。。。完全没用到 python 高效的东西，只用了最最基本的函数，太弱智了
1 #为方便本地调试，加了很多 print，提交的时候需要注释掉 2 def snail(array): 3 ans = [] 4 if len(array) == 1: # preven "index out of range"!!! 5 ans = array[0] 6 #print ans 7 return ans 8 len_row = len(array) - 1 9 len_col = len(array[1]) - 1 10 all = (len_row + 1) * (len_col +1 ) 11 #print len_col 12 over_row = 0 13 over_col = 0 14 while over_col <= len_col/2: 15 row = over_row # current row 16 col = over_col 17 while over_col <= col < len_col - over_col: 18 now = array[row][col] 19 ans.append(now) 20 col += 1 21 #print 'now == ', now 22 #print 'this row over, col ==', col 23 24 while over_row <= row < len_row - over_row : 25 now = array[row][col] 26 ans.append(now) 27 row += 1 28 #print 'now == ', now 29 #print 'this col over, row ==', row 30 31 while over_col < col <= len_col - over_col: 32 now = array[row][col] 33 ans.append(now) 34 col -= 1 35 #print 'now == ', now 36 #print 'this reverse row over, col ==', col 37 38 while over_row < row <= len_row - over_row: 39 now = array[row][col] 40 ans.append(now) 41 row -= 1 42 #print 'now == ', now 43 #print 'this reverse col over, col ==', row 44 45 over_row += 1 46 over_col += 1 47 #print 'print over_row == ', over_row, 'print over_col == ', over_col 48 if len(ans) < all: 49 last = int(len_row/2) 50 ans.append(array[last][last]) 51 #print ans 52 return ans
