字符二分快速查找

import java.util.Scanner;


/**
 * 
 * @author luozhonghua
 *
 */
public class charSearchAndSort {

	 static void kuaiSu(char[] a,int left,int right)             //字符快速排序  
	    {  
	        int f,l,r;  
	        char t;  
	  
	        l=left;  
	        r=right;  
	        f=a[(left+right)/2];  
	        
	        while(l<r){  
	            while(a[l]<f) ++l;  
	            while(a[r]>f) --r;  
	            if(l<=r){  
	                t=a[l];  
	                a[l]=a[r];  
	                a[r]=t;  
	                ++l;  
	                --r;  
	            }  
	        }  
	        
	        if(l==r)  l++;  
	        if(left<r) kuaiSu(a,left,l-1);                 //递归调用  
	        if(l<right) kuaiSu(a,r+1,right);                //递归调用  
	    }  
 
	 static int searchFun(char []a,int n,char x){                     //折半查找
		    int mid,low,high;
			low=0;
			high=n-1;
		    while(low<=high){
		   		mid=(low+high)/2;
				if(a[mid]==x)
		            return mid;						//找到
				else if(a[mid]>x)
				    high=mid-1;
		        else
					low=mid+1;
		    }
			return -1;								//未找到
		}
	 
	    public static void main(String[] args)   
	    {  
	        char[] str=new char[80];  
	        int N;
	        char[] x=new char[80];
	  
	        System.out.print("输入一个字符串:");  
	        Scanner input=new Scanner(System.in);  
	        str=input.next().toCharArray();                         //输入字符串  
	        N=str.length;     
	        System.out.print("排序前：\n");  
	        System.out.println(str);                //输出  
	        kuaiSu(str,0,N-1);                      //二分排序  
	        System.out.print("排序后：\n");  
	        System.out.print(str);              //输出  
 
	        //二分查找
	        System.out.print("\n");
	        System.out.println("输入要查找的字符:");
		    Scanner inpu=new Scanner(System.in);
		    x=inpu.next().toCharArray();							//输入要查找的数

		   int n=searchFun(str,N,x[0]);						//查找
		    if(n<0)								//输出查找结果
	           System.out.println("没找到数据:"+x);
			else
			   System.out.println("数据:"+x[0]+" 位于数组的第"+(n+1)+" 个元素处。");
	   
	    }  
}