java练习

输入一个数字将其倒置后返回差

import java.util.Scanner;
	/**
	 * @param Liusasa
	 */
public class test {

	public static int daozhicha(int a){
		String s = String.valueOf(a);
		int[] ar = new int[s.length()];
		int n = 0;	
		double re;
		for(int i = 0;i<ar.length;i++){
			ar[i] = s.charAt(ar.length-1-i)-'0';
		}
		n = ar[ar.length-1];
		for(int i = ar.length-2;i>=0;i-- ){
			re = Math.pow(10,ar.length-1-i);
			n += ar[i]*re;
		}
		System.out.println("转置后："+n);
		return n-a;
}
	public static void main(String[] args) {
		System.out.println("请输入想处理的数字：");
		System.out.printf(">>>");
		Scanner in = new Scanner(System.in);
		int a = in.nextInt();
		System.out.println("转置前-转置后："+daozhicha(a));
	}

}

给定一个非0有序数组a，插入一个值n使数组仍有序

package demo1;

import java.util.Scanner;

/**给定一个非0有序数组a[10]={1,2,3,4,5,6,7,8,9,0}
 * 插入一个值n使
 * @Liusasa
 */
public class test {

	public static void insert(int a[],int n){
		int t1,t2;
		int j;
		for(int i= 0;i<a.length;i++){
			if(n<=a[i]){
					t1=a[i];
					a[i]=n;
					
					for(;i<a.length-1;i++){
						
						t2 = a[i+1];
						a[i+1] = t1;
						t1 = t2;
						
					}
					//a[i]=n;
					break;
				
			}
			
		}

	} 
	public static void main(String[] args) {
		int[] a= new int[] {1,2,3,4,5,6,7,8,9,0};
		int n;
		Scanner in = new Scanner(System.in);
//		System.out.println("请输入数组a");
//		for(int i = 0;i<a.length-1;i++){
//			a[i] = in.nextInt();
//		}
		
		System.out.println("请输入数字n");
		n = in.nextInt();
		insert(a,n);
		
		
		for(int x:a){
			System.out.printf("%s ",x);
		}
		//System.out.println(a.length);
	}

}

 用Hashmap统计字母个数

import java.util.*;



/**
 * @param Liusasa
 */

public class test {

	public static void main(String[] args) {
		String str = "FFEEFEAAECFFBDBFBCDADACDEEDCCFFAFADEFBBAFDCDDCDBFEFCEDDBFDBEEFCAAEECEECDCDECADDCDFAEACECFEADCBFECADFDFBAAADCFAFFCEADFDDAEAFAFFDEFECEDEEEDFBDBFDDFFBCFACECEDCAFAFEFAFCDBDCCBCCEADADAEBAFBACACBFCBABFDAFBEFCFDCFBCEDCEAFBCDBDDBDEFCAAAACCFFCBBAAEECFEFCFDEEDCACDACECFFBAAAFACDBFFAEFFCCCDBFADDDBEBCBEEDDECFAFFCDEAFBCBBCBAEDFDBEBBBBABBFDECBCEFAABCBCFFBDBACCFFABEAEBEACBBDCBCCFADDCACFDEDECCCBFAFCBFECAACAFBCFBAF";
		Map<Character,Integer> mp = new HashMap();
		
		for(int i=0;i<str.length();i++)
		{
			if(mp.containsKey(str.charAt(i))){
				int k = mp.get(str.charAt(i));
				//mp.replace(str.charAt(i),k+1);
				mp.remove(str.charAt(i));
				mp.put(str.charAt(i),k+1);
				
			}else{
				mp.put(str.charAt(i),1);
			}
		}
//		for(int j=0;j<str.length();j++){
//			mp.get(str.charAt(j));
//		}
		System.out.println(mp);
		
	}

}