package com.java.recursion;
/**
* @描述 三種方法實(shí)現(xiàn)斐波那契數(shù)列
* @項(xiàng)目名稱 Java_DataStruct
* @包名 com.java.recursion
* @類名 Fibonacci
* @author chenlin
*/
public class Fibonacci {
/**
* 題目：古典問(wèn)題：有一對(duì)兔子，從出生后第3個(gè)月起每個(gè)月都生一對(duì)兔子，小兔子長(zhǎng)到第三個(gè)月后每個(gè)月又生一對(duì)兔子，假如兔子都不死，
* 問(wèn)每個(gè)月的兔子總數(shù)為多少？
* month 1 2 3 4 5 6
* borth 0 0 1 1 2 3
* total 1 1 2 3 5 8
*/
  /**
   * 疊加法
   *
   * @param month
   * @return
   */
  public static int getTotalByAdd(int month) {
    int last = 1;//上個(gè)月的兔子的對(duì)數(shù)
    int current = 1;//當(dāng)月的兔子的對(duì)數(shù)
    int total = 1;
    for (int i = 3; i <= month; i++) {
      //總數(shù)= 上次+當(dāng)前
      total = last + current;
      last= current ;
      current = total;
    }
    return total;
  }
  /**
   * 使用數(shù)組
   *
   * @param month
   * @return
   */
  public static int getTotalByArray(int month) {
    int arr[] = new int[month];
    arr[1] = arr[2] = 1;
    for (int i = 2; i < month; i++) {
      arr[i] = arr[i - 1] + arr[i - 2];
    }
    return arr[month - 1] + arr[month - 2];
  }
  public static int getTotalByRecusion(int month) {
    if (month == 1 || month == 2) {
      return 1;
    } else {
      return getTotalByRecusion(month - 1) + getTotalByRecusion(month - 2);
    }
  }
  public static void main(String[] args) {
    System.out.println("腳本之家測(cè)試結(jié)果：");
    System.out.println(getTotalByAdd(3));
    System.out.println(getTotalByAdd(4));
    System.out.println(getTotalByAdd(5));
    System.out.println(getTotalByAdd(6));
  }
}