递归问题求解学习一

http://blog.csdn.net/lixiaoshan_18899/archive/2006/09/15/1227122.aspx

http://www.zxbc.cn/html/20070920/27182.html

http://www.cnblogs.com/jillzhang/archive/2007/10/06/915035.html

http://www.cnblogs.com/zhangqqqf/archive/2008/09/12/1289730.html

递归实现1

/**
	 * 递归实现N的阶乘
	 * @param n 
	 * @return return the value of n!
	 */
	public static int fun(int n){
		int intRe = 0;
		if(n==0 || n==1){
			intRe = 1;
		}
		if(n>1){
			intRe = n * fun(n-1);
		}
		return intRe;
	}
	
	/**
	 * 非递归实现N的阶乘
	 * @param n
	 * @return
	 */
	public static int fun2(int n){
		int intRe = 1;
		if(n==0 || n==1){
			intRe = 1;
		}
		if(n>1){
			for(int i=n;i>1;i--){
				intRe = intRe * i;
			}
		}
		return intRe;
	}

递归实现2

/**
	 * 递归实现汉诺塔问题
	 * @param num num is the disk number
	 * @param from src A
	 * @param mid middle B 
	 * @param to dis C
	 */
	public static void move(int num,String from,String mid,String to){
		if(num==1){
			System.out.println("move disk from " + from + " to " + to);
		}else{
			move(num-1,from,to,mid);
			System.out.println("move disk from "+ from + " to " + to);
			move(num-1,mid,from,to);
			
		}
	}

递归实现3

/**
	 * 非递归实现数组的逆序
	 * reverseArray Non-recursive method
	 * @param array
	 * @return
	 */
	public static String[] reverseArray(String[] array){
		int length = array.length;
		String [] strArray = new String[length];
		int i=0;
		for( ;i<length-1;){
			for(int j=length-1;j>=0;j--){
				strArray[i] = array[j];
				i++;
			}
			
		}
		return strArray;
		
	}
	
	/**
	 * 递归实现数组的逆序
	 * @param array
	 * @param row
	 * @param high
	 */
	public static void reverseArray2(String[] array ,int row,int high){
		String temp = array[row];
		array[row] = array[high];
		array[high] = temp;
		row ++;
		high--;
		
		int len = array.length;
		int m = (len-1)%2;
		
		if(m==0 && row!=high){
			reverseArray2(array, row, high);
		}
		if(m!=0 && high>=row+1){
			reverseArray2(array, row, high);
		}
	}
	
	/**
	 * 递归实现数组的逆序
	 * @param array
	 * @param row
	 * @param high
	 */
	public static void reverseArray3(String[] array ,int row,int high){
		String temp = array[row];
		array[row] = array[high];
		array[high] = temp;
		if(row>=high)
			return;
		else{
			reverseArray2(array, row+1, high-1);
		}
		
	}

递归实现数组逆序类

public class RecursiveArray {
	
	private String[] array = null;
	
	public RecursiveArray(String[] array){
		this.array = array;
	}
	
	public void resevert(int i,int j){
		String temp = array[i];
		array[i] = array[j];
		array[j] = temp;
		if(i>=j)
			return;
		else{
			resevert(i+1,j-1);
		}
		
	}
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		String arr[] = {"23","44","55","66","77"};
		int len = arr.length;
		RecursiveArray recur = new RecursiveArray(arr);
		recur.printArr();
		recur.resevert(0, len-1);
		recur.printArr();
	}
	private void printArr() {
		if(array != null){
			for(int i=0;i<array.length;i++){
				System.out.println(array[i]);
			}
			System.out.println("-----------------");
		}
	}
}