最強最速アルゴリズマー養成講座P63より

gistfile1.d

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

void main()
{
  auto first = ["fishing", "gardening", "swimming", "fishing"];
  auto second = ["hunting", "fishing", "fishing", "biting"];
  writeln((new InterestingParty()).bestInvitation(first, second));
}

class InterestingParty
{
  int bestInvitation(string[] first, string[] second)
  {
    int[string] counting;
    foreach (interesting; zip(first, second)) {
      counting[interesting[0]]++;
      counting[interesting[1]]++;
    }

    return counting.values.sort.reverse[0];
  }

  unittest
  {
    auto first = ["fishing", "gardening", "swimming", "fishing"];
    auto second = ["hunting", "fishing", "fishing", "biting"];
    auto result = 4;
    assert(result == (new InterestingParty()).bestInvitation(first, second));
  }

  unittest
  {
    auto first = ["variety", "diversity", "loquacity", "courtesy"];
    auto second = ["talking", "speaking", "discussion", "meeting"];
    auto result = 1;
    assert(result == (new InterestingParty()).bestInvitation(first, second));
  }

  unittest
  {
    auto first = ["snakes", "programming", "cobra", "monty"];
    auto second = ["python", "python", "anaconda", "python"];
    auto result = 3;
    assert(result == (new InterestingParty()).bestInvitation(first, second));
  }
}