请教一道没见过的Facebook电面题

给你一个array of strings，要求按顺序在

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thon3磕磕碰碰写下来的code，发现好多edge case要处理。。有没有大神会更好的写法？

1. <div style="color: rgb(248, 248, 242); background-color: rgb(39, 40, 34); font-family: Monaco; font-size: 13px; line-height: 20px; white-space: pre;"><div><span style="color: #66d9ef;font-style: italic;">def</span> <span style="color: #a6e22e;">assign_words</span>(<span style="color: #fd971f;font-style: italic;">grid</span>, <span style="color: #fd971f;font-style: italic;">words</span>):</div><div>    i <span style="color: #f92672;">=</span> <span style="color: #ae81ff;">0</span></div><div>    <span style="color: #f92672;">for</span> row <span style="color: #f92672;">in</span> <span style="color: #66d9ef;">range</span>(<span style="color: #66d9ef;">len</span>(grid)):</div><div>        <span style="color: #f92672;">for</span> col <span style="color: #f92672;">in</span> <span style="color: #66d9ef;">range</span>(<span style="color: #66d9ef;">len</span>(grid[row])):</div><div>            grid[row][col] <span style="color: #f92672;">=</span> words[i]</div><div>            i <span style="color: #f92672;">+=</span> <span style="color: #ae81ff;">1</span></div><div>            <span style="color: #f92672;">if</span> i <span style="color: #f92672;">==</span> <span style="color: #66d9ef;">len</span>(words):</div><div>                <span style="color: #f92672;">return</span></div>
   
2. 
   
3. <div><span style="color: #66d9ef;font-style: italic;">def</span> <span style="color: #a6e22e;">print_words</span>(<span style="color: #fd971f;font-style: italic;">words</span>):</div><div>  word_count <span style="color: rgb(249, 38, 114);">=</span> <span style="color: rgb(102, 217, 239);">len</span>(words)</div><div>  rows <span style="color: #f92672;">=</span> word_count <span style="color: #f92672;">//</span> <span style="color: #ae81ff;">3</span></div><div>  extra_columns <span style="color: #f92672;">=</span> word_count <span style="color: #f92672;">%</span> <span style="color: #ae81ff;">3</span></div>
   
4. <div>  grid <span style="color: #f92672;">=</span> [[<span style="color: #e6db74;">''</span>] <span style="color: #f92672;">*</span> <span style="color: #ae81ff;">3</span> <span style="color: #f92672;">for</span> _ <span style="color: #f92672;">in</span> <span style="color: #66d9ef;">range</span>(rows)]</div>
   
5. <div>  <span style="color: #75715e;"># special case</span></div><div>  <span style="color: #f92672;">if</span> word_count <span style="color: #f92672;"><=</span> <span style="color: #ae81ff;">3</span>:</div><div>    grid.append([<span style="color: #e6db74;">''</span>]<span style="color: #f92672;">*</span><span style="color: #ae81ff;">3</span>)</div><div>    assign_words(grid, words)</div><div>    <span style="color: #f92672;">for</span> row <span style="color: #f92672;">in</span> grid:</div><div>        <span style="color: #66d9ef;">print</span> (<span style="color: #e6db74;">' '</span>.join(row))</div><div>    <span style="color: #f92672;">return</span></div><div>    </div><div>  <span style="color: #f92672;">if</span> extra_columns <span style="color: #f92672;">==</span> <span style="color: #ae81ff;">1</span>:</div><div>      <span style="color: #f92672;">if</span> rows <span style="color: #f92672;">></span> <span style="color: #ae81ff;">2</span>:</div><div>          grid[<span style="color: #ae81ff;">0</span>].append(<span style="color: #e6db74;">''</span>)</div><div>      <span style="color: #f92672;">elif</span> rows <span style="color: #f92672;">==</span> <span style="color: #ae81ff;">2</span>:</div><div>          grid[<span style="color: #ae81ff;">1</span>].pop()</div><div>          grid.append([<span style="color: #e6db74;">''</span>]<span style="color: #f92672;">*</span><span style="color: #ae81ff;">3</span>)</div><div>  <span style="color: #f92672;">elif</span> extra_columns <span style="color: #f92672;">==</span> <span style="color: #ae81ff;">2</span>:</div><div>      <span style="color: #f92672;">if</span> rows <span style="color: #f92672;">></span> <span style="color: #ae81ff;">2</span>:</div><div>          grid[<span style="color: #ae81ff;">0</span>].append(<span style="color: #e6db74;">''</span>)</div><div>          grid[<span style="color: #ae81ff;">1</span>].append(<span style="color: #e6db74;">''</span>)</div><div>      <span style="color: #f92672;">else</span>:</div><div>          grid.append([<span style="color: #e6db74;">''</span>]<span style="color: #f92672;">*</span><span style="color: #ae81ff;">3</span>)</div><div>  </div><div>  assign_words(grid, words)</div>
   
6. <div>  <span style="color: #75715e;"># special case</span></div><div>  <span style="color: #f92672;">if</span> <span style="color: #ae81ff;">3</span> <span style="color: #f92672;"><</span> word_count <span style="color: #f92672;"><</span> <span style="color: #ae81ff;">6</span>:</div><div>      <span style="color: #66d9ef;">print</span> (grid[<span style="color: #ae81ff;">0</span>][<span style="color: #ae81ff;">0</span>]<span style="color: #f92672;">+</span> <span style="color: #e6db74;">' '</span><span style="color: #f92672;">+</span>grid[<span style="color: #ae81ff;">0</span>][<span style="color: #ae81ff;">2</span>]<span style="color: #f92672;">+</span><span style="color: #e6db74;">' '</span><span style="color: #f92672;">+</span>grid[<span style="color: #ae81ff;">1</span>][<span style="color: #ae81ff;">1</span>])</div><div>      <span style="color: #66d9ef;">print</span> (grid[<span style="color: #ae81ff;">0</span>][<span style="color: #ae81ff;">1</span>]<span style="color: #f92672;">+</span> <span style="color: #e6db74;">' '</span><span style="color: #f92672;">+</span>grid[<span style="color: #ae81ff;">1</span>][<span style="color: #ae81ff;">0</span>]<span style="color: #f92672;">+</span><span style="color: #e6db74;">' '</span><span style="color: #f92672;">+</span>grid[<span style="color: #ae81ff;">1</span>][<span style="color: #ae81ff;">2</span>])</div><div>      <span style="color: #f92672;">return</span></div>
   
7. <div>  <span style="color: #75715e;"># print grid</span></div><div>  <span style="color: #f92672;">for</span> col <span style="color: #f92672;">in</span> <span style="color: #66d9ef;">range</span>(<span style="color: #66d9ef;">len</span>(grid[<span style="color: #ae81ff;">0</span>])):</div><div>      <span style="color: #f92672;">for</span> row <span style="color: #f92672;">in</span> <span style="color: #66d9ef;">range</span>(<span style="color: #66d9ef;">len</span>(grid)):</div><div>          <span style="color: #f92672;">if</span> col <span style="color: #f92672;">==</span> <span style="color: #66d9ef;">len</span>(grid[row]):</div><div>              <span style="color: #f92672;">break</span></div><div>          <span style="color: #66d9ef;">print</span> (grid[row][col], <span style="color: #fd971f;font-style: italic;">end</span><span style="color: #f92672;">=</span><span style="color: #e6db74;">' '</span>)</div><div>      <span style="color: #66d9ef;">print</span> ()</div></div>

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1. def assign_words(grid, words):
   
2.     i = 0
   
3.     for row in range(len(grid)):
   
4.         for col in range(len(grid[row])):
   
5.             grid[row][col] = words[i]
   
6.             i += 1
   
7.             if i == len(words):
   
8.                 return
   
9. 
   
10. 
    
11. def print_words(input):
    
12.   words = sorted(input.split())
    
13.   word_count = len(words)
    
14.   rows = word_count // 3
    
15.   extra_columns = word_count % 3
    
16. 
    
17.   grid = [[''] * 3 for _ in range(rows)]
    
18. 
    
19.   # special case
    
20.   if word_count <= 3:
    
21.     grid.append(['']*3)
    
22.     assign_words(grid, words)
    
23.     for row in grid:
    
24.         print (' '.join(row))
    
25.     return
    
26.    
    
27.   if extra_columns == 1:
    
28.       if rows > 2:
    
29.           grid[0].append('')
    
30.       elif rows == 2:
    
31.           grid[1].pop()
    
32.           grid.append(['']*3)
    
33.   elif extra_columns == 2:
    
34.       if rows > 2:
    
35.           grid[0].append('')
    
36.           grid[1].append('')
    
37.       else:
    
38.           grid.append(['']*3)
    
39.   
    
40.   assign_words(grid, words)
    
41. 
    
42.   # special case
    
43.   if 3 < word_count < 6:
    
44.       print (grid[0][0]+ ' '+grid[0][2]+' '+grid[1][1])
    
45.       print (grid[0][1]+ ' '+grid[1][0]+' '+grid[1][2])
    
46.       return
    
47. 
    
48.   # print grid
    
49.   for col in range(len(grid[0])):
    
50.       for row in range(len(grid)):
    
51.           if col == len(grid[row]):
    
52.               break
    
53.           print (grid[row][col], end=' ')
    
54.       print ()

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代码炸了

有哪些edge case,求给几个例子?

oio14644 发表于 2018-2-26 12:35
有哪些edge case,求给几个例子?

我的code在array length <= 3, 3 < array length < 6, array length > 6的3种情况得分开来算。

1.    
   
2. def print_words(words):
   
3.         columns, dangling = divmod(len(words), 3)
   
4.         iterator = iter(words)
   
5.         columns = [take(columns + (dangling > i), iterator) for i in range(3)]
   
6.         for row in itertools.zip_longest(*columns, fillvalue=''):
   
7.             print('{}  {}  {}'.format(*row))

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stack exchange上某大神的solution。

1.     void print_3column(string str) {
   
2.         int N = str.size();
   
3.         int ave = N / 3;
   
4.         int ext = N % 3;
   
5.         int total = 0;
   
6.         for (int row = 0; row < ave + (ext ? 1 : 0); ++row) {
   
7.             for (int i = 0; i < 3 && total < N; ++i) {
   
8.                 int index = i * ave + min(i, ext) + row;
   
9.                 cout<<str[index]<<" ";
   
10.                 ++total;
    
11.             }
    
12.             cout<<endl;
    
13.         }
    
14.     }
    

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想了下不用模的解法。题目很简单，高效的code感觉不是那么容易写的

1. // Example program
   
2. #include <iostream>
   
3. #include <string>
   
4. 
   
5. using namespace std;
   
6. void print_Ncolumns(string str, int N=3){
   
7.     int j=0;
   
8.     for(int i=0;i<str.size();++i,++j){
   
9.         j = (j==N?0:j);
   
10.         cout<<str[i];
    
11.         if(j == N-1)
    
12.             cout<<endl;
    
13.         else
    
14.             cout<<" ";
    
15.     }
    
16.    
    
17.     if(j!=N)
    
18.     cout<<endl;
    
19. }
    
20. 
    
21. int main()
    
22. {
    
23.     print_Ncolumns("");
    
24.     print_Ncolumns("abcdefg");
    
25.     print_Ncolumns("abs");
    
26.     print_Ncolumns("ab");
    
27.     print_Ncolumns("abcd");
    
28. }
    

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1. def print_chars(chars)
   
2.   return if chars.nil? || chars.empty?
   
3. 
   
4.   ave = chars.length / 3
   
5.   remainder = chars.length % 3
   
6.   row = ave + (remainder.zero? ? 0 : 1)
   
7.   col = 3
   
8.   
   
9.   (0...row).each do |i|
   
10.     delta = remainder > 0 ? 1 : 0
    
11.     col = remainder if i == row - 1 && remainder != 0
    
12. 
    
13.     (0...col).each do |j|
    
14.       index = i + ave * j + (j > 0 ? delta : 0)
    
15.       delta += 1 if j > 0 && remainder == col - 1 && delta != 0
    
16.       print chars[index]
    
17.     end
    
18.     puts ''
    
19.   end
    
20. end
    
21. 
    
22. 
    
23. print_chars(['a','b','c','d','e','f','g', 'i'])

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这个是原题吧        
Text Justification