Entry

プログラミング・メモ - Java プログラマもスタックサイズには要注意の巻

2008年12月15日

この前ちょっと書いた最大値を求める話で，とむよんさんのこちらのコードから（インデント変えてます）。

public class Moge {

  public static void main(String[] args) {
    int[] a = {1,5,2,3,6,4};
    System.out.println(Moge.max(a)); //output '6'
  }

  public static int max(int[] a){
    return Moge._max(a, 0, a[0]);
  }

  private static int _max(int[] a, int ind, int max){
    if(a.length-1 == ind) return max;
    return Moge._max(a, ind+1, Math.max(a[ind], a[ind+1]));
  }
}

あまりスマートでは無いですが。。

codeなにがし::最大値の取得（ｊava）

再帰を使う方法。スタックに積むのにオーバーヘッドがかかるんですけれど，ソートよりはずっと性能はいいはず。最大値ひとつ見つけるのに，O(N**2) （あるいは O(Nlog(N))）ってねぇ……（←しつこい）。

再帰を使う方法は，見た目がスマートなもんでウケる人にはウケるんですけれど，ひとつ気をつけなくちゃいけないのが，スタックサイズです。for-文でクルクルやる時は，int をインデックスにすると，2^31-1まで数えられるけど，通常，スタックサイズはこれよりずっと小さい。

つことで試してみた。

public class Moge {
  public static void main(String[] args) {
    int[] a = {
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6
      };
    System.out.println(Moge.max(a)); //output '9'
  }
  
  public static int max(int[] a){
    return Moge._max(a, 0, a[0]);
  }
  
  private static int _max(int[] a, int ind, int max){
    if(a.length-1 == ind) return max;
    return Moge._max(a, ind+1, Math.max(a[ind], a[ind+1]));
  }
}

普通にコンパイルできます。ただ，実行すると，

Exception in thread "main" java.lang.StackOverflowError
    at Moge._max(Moge.java:230)
    at Moge._max(Moge.java:230)
    at Moge._max(Moge.java:230)
    at Moge._max(Moge.java:230)
    at Moge._max(Moge.java:230)
    at Moge._max(Moge.java:230)
    at Moge._max(Moge.java:230)
    at Moge._max(Moge.java:230)
    :

スタックを使い果たして死んでしまいます。Java で StackOverflowError が出るところって見たことなかったんですけど，やっぱ出るときゃ出るんですね（何言ってんだか）。

もちろん，こっちだと普通に動きます（配列の部分は省略）。当たり前ですが。多分，StackOverflowError が出ない大きさの配列の場合であっても，こっちの方がスタックに積まない分だけ若干速い。C/C++ なら，ポインタを使ってもっと速くできる。ま，そんなに速くすることもないんですが。

public class Moge {
  public static void main(String[] args) {
    int[] a = {
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,4,9,3,9,4,1,5,2,3,6,
      :
      };
    int max = a[0];
    for (int i = 0; i < a.length; i++) {
      max = (max < a[i]) ? a[i] : max;
    }
    System.out.println(max); //output '9'
  }
}

codeなにがしのお題では，配列の大きさが明示されていなかったので（「多量」らしい），スタックサイズが十分にあると想定するのは危険なのかも。と，外野でゴニョゴニョ。

Related Books ?
Trackback
Trackback URL:
Ads
About
Search This Site
Ads
Categories
Recent Entries
Plugin TEST (del.icio.us)
Log Archive
2010-03 2010-02 2010-01 2009-12 2009-11 2009-10 2009-09 2009-08 2009-07 2009-06 2009-05 2009-04 2009-03 2009-02 2009-01 2008-12 2008-11 2008-10 2008-09 2008-08 2008-07 2008-06 2008-05 2008-04 2008-03 2008-02 2008-01 2007-12 2007-11 2007-10 2007-09 2007-08 2007-07 2007-06 2007-05 2007-04 2007-03 2007-02 2007-01 2006-12 2006-11 2006-10 2006-09 2006-08 2006-07 2006-06 2006-05 2006-04 2006-03 2006-02 2006-01 2005-12 2005-11 2005-10 2005-09 2005-08 2005-07 2005-06 2005-05 2005-04 2005-03 2005-02 2005-01 2004-12 2004-11 2004-10 2004-09 2004-08 2004-07 2004-06 2004-05 2004-04 2004-03 2004-02 2004-01 2003-12 qune@Hatena
Syndicate This Site
RSS 1.0
RSS 2.0
Atom 0.3
Info.
クリエイティブ・コモンズ・ライセンス
Movable Type 3.36
Valid XHTML 1.1!
Valid CSS!

© 2003-2010 AIAN