転置文字列

gistfile1.d

import std.stdio;
import std.algorithm;
import std.range;

void main()
{
  auto str_list = [
    "abcdefg",
    "dlang",
    "qwerty",
    "hello world!",
    ];

  writeln(str_list);
  writeln(str_list.transpose);
}

string[] transpose(string[] str_list)
{
  auto width = str_list.reduce!((s1, s2) => (s1.length < s2.length) ? s2 : s1).length;
  auto height = str_list.length;

  string[] trans_str_list;
  trans_str_list.length = width;

  foreach (i; iota(height)) {
    foreach (j; iota(width)) {
      trans_str_list[j] ~= (j < str_list[i].length) ? str_list[i][j] : ' ';
    }
  }

  return trans_str_list;
}

unittest
{
  auto sut = [
    "12",
    "34",
    ];
  auto expected = [
    "13",
    "24",
    ];
  assert(sut.transpose == expected);
}

unittest
{
  auto sut = [
    "abc",
    ];
  auto expected = [
    "a",
    "b",
    "c",
    ];
  assert(sut.transpose == expected);
}

unittest
{
  auto sut = [
    "abcd",
    "efg",
    "hi",
    ];
  auto expected = [
    "aeh",
    "bfi",
    "cg ",
    "d  ",
    ];
  assert(sut.transpose == expected);
}