/**
 * 棧方式非遞歸漢諾塔
 * @author zy
 *
 */
public class StackHanoi
{
  /**
   * @param args
   */
  public static void main(String[] args)
  {
    System.out.println("腳本之家測試結果：");
    System.out.println("遞歸方式：");
    hanoiNormal(3, 'A', 'B', 'C');
    System.out.println();
    System.out.println("非遞歸方式：");
    hanoi(3, 'A', 'B', 'C');
  }
  /**
   * 遞歸漢諾塔
   * @param n
   * @param A
   * @param B
   * @param C
   */
  public static void hanoiNormal(int n, char A, char B, char C)
  {
    //hanoiNormal(1, A, B, C)等價于直接移動A到C（ move(A,C) ）
    if(n==1)
    {
      move(A, C);
      return;
    }
    else
    {
      hanoiNormal(n-1, A, C, B);
      move(A, C);
      hanoiNormal(n-1, B, A, C);
    }
  }
  /**
   * 非遞歸漢諾塔
   * @param n
   * @param A
   * @param B
   * @param C
   */
  public static void hanoi(int n, char A, char B, char C)
  {
    //創(chuàng)建一個棧
    StateStack s = new StateStack();
    //將開始狀態(tài)進棧
    s.push( new State(n, A, B, C) );
    //保存出棧元素
    State state = null;
    //出棧
    while((state = s.pop()) != null)
    {
      //如果n為1( hanoi(1,A,B,C) )，直接移動A->C
      if(state.n == 1)
      {
        move(state.A, state.C);
      }
      //如果n大于1，則按照遞歸的思路，先處理hanoi(n-1,A,C,B)，再移動A->C(等價于hanoi(1,A,B,C) ),然后處理hanoi(n-1,B,A,C)，因為是棧，所以要逆序添加
      else
      {
        //棧結構先進后出，所以需要逆序進棧
        s.push( new State(state.n-1, state.B, state.A, state.C) );
        s.push( new State(1, state.A, state.B, state.C) );
        s.push( new State(state.n-1, state.A, state.C, state.B) );
      }
    }
  }
  /**
   * 從s到d移動盤子
   */
  public static void move(char s, char d)
  {
    System.out.println(s+"->"+d);
  }
}
//狀態(tài)
class State
{
  public int n;
  public char A;
  public char B;
  public char C;
  public State(int n, char A, char B, char C)
  {
    this.n = n;
    this.A = A;
    this.B = B;
    this.C = C;
  }
}
//棧
class StateStack
{
  private State[] storage = new State[1000];
  //棧頂
  private int top = 0;
  //入棧
  public void push(State s)
  {
    storage[top++] = s;
  }
  //出棧
  public State pop()
  {
    if(top>0)
    {
      return storage[--top];
    }
    return null;
  }
}