字母表炮

Question

发射一个炮弹，使它在飞行的第一次眨眼时通过N树梢上升，在第二次眨眼时由N-1树顶上升，直到到达轨道的最高点。然后，它开始下降1，2，等等，每眨眼树梢，直到它击中地面。同时，炮弹水平移动，速度为1树梢/眼。

你的任务是用英语字母表中的连续字母画出轨迹。如果您的字母用完了，请从'A'重新开始。编写函数或程序。输入是整数N (1≤N≤15)。输出可以是任何合理形式的字符矩阵，例如换行符分隔的字符串或字符串列表。字母可以全小写，也可以大写。允许额外的前导和尾随空间。标准漏洞是被禁止的。更短的代码更好。

in:
5
out:
    OP
   N  Q
   M  R
  L    S
  K    T
  J    U
 I      V
 H      W
 G      X
 F      Y
E        Z
D        A
C        B
B        C
A        D

in:
1
out:
AB

Answer 1

马蒂尔，29字节

,G:tPY"tf1Y2y@?tn+P])Z?]Pv1X!

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是如何工作的

,        % Do twice
  G:     %   Push [1 2 ... n], where n is the input
  tP     %   Duplicate, flip: pushes [n n-1 ... 1]
  Y"     %   Run-length decoding: gives vector with n ones, n-1 twos ... (*)
  tf     %   Duplicate, find: gives [1 2 3 ... n*(n-1)/2] (**)
  1Y2    %   Push string 'ABC...Z'
  y      %   Duplicate from below: pushes [1 2 3 ... n*(n-1)/2]  again
  @?     %   If we are in the second iteration
    tn   %     Duplicate, length: pushes n*(n-1)/2
    +    %     Add: gives [n*(n-1)/2+1 n*(n-1)/2+2 ... n*(n-1)*2] 
    P    %     Flip: gives [n*(n-1)/2 n*(n-1)/2-1 ... n*(n-1)/2+1]
  ]      %   End if
  )      %   Index (1-based, modular) into the string. Gives a substring
         %   with the letters of one half of the parabola (***)
  Z?     %   Sparse: creates a char matrix with the substring (***) written
         %   at specified row (*) and column (**) positions. The remaining
         %   positions contain char(0), which will be displayed as space
]        % End do twice. We now have the two halves of the parabola, but
         % oriented horizontally instead of vertically
P        % Flip the second half of the parabola vertically, so that the
         % vertex matches in the two halves
v        % Concatenate the two halves vertically
1X!      % Rotate 90 degrees, so that the parabola is oriented vertically.
         % Implicitly display

Answer 2

C，184个字节

i,j,k,l,m,h,o;f(n){char L[o=n*n][n*3];for(i=o;i--;)for(L[i][j=n*2]=h=k=0;j--;)L[i][j]=32;for(m=n;!h|~i;m-=1-h*2)for(h+(l=m)?++j:++h;l--;)L[h?i--:++i][j]=65+k++%26;for(;o--;)puts(L+o);}

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展开：

i, j, k, l, m, h, o;
f(n)
{
    char L[o=n*n][n*3];

    for (i=o; i--;)
        for (L[i][j=n*2]=h=k=0; j--;)
            L[i][j] = 32;

    for (m=n; !h|~i; m-=1-h*2)
        for (h+(l=m)?++j:++h; l--;)
            L[h?i--:++i][j] = 65 + k++%26;

    for (; o--;)
        puts(L+o);
}

Answer 3

Java (OpenJDK 8)，121个字节

n->{for(int l=n*++n/2,r=l,i=1,j=0;l>0;j=j-->0?j:i++)System.out.printf("%"+(n-i)+"c%"+(2*i-1)+"c%n",--l%26+65,r++%26+65);}

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解释

n->{                             // int-accepting consumer
 for(                            //  loop
   int l=n*++n/2,                //    declare l (left) is the first character to print.
                                 //              Oh, and n is increased to reduce byte count later.
       r=l,                      //            r (right) is the second character to print.
       i=1,                      //            i is the "outer-loop" index
       j=0;                      //            j is the "inner-loop" index
   l>0;                          //    while there are characters to print        
   j=j-->0?j:i++)                //    simulate two loops in one,
                                 //      where j starts from 0 and always decreases until it reaches 0
                                 //      at which point j is reset to i and i is increased
  System.out.printf(             //   Print...
   "%"+(n-i)+"c%"+(2*i-1)+"c%n", //    2 characters
                                 //    - the first with n-i-1 whitespaces (remember, n was increased)
                                 //    - the second characters with 2*i-2 whitespaces
   --l%26+65,                    //    the first character to print is the left one, we decrease it.
   r++%26+65                     //    the second character to print is the right one, we increase it.
  );                             //   
                                 //  end loop
}                                // end consumer