算法集合

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1 写一个函数，输入int型，返回整数逆序后的字符串。

public static void main(String[] args) {    System.out.println("开始");    System.out.println(fun(1234587512));    System.out.println("结束");}private static String fun(int arg0){    if(arg0/10>0){        return arg0%10+String.valueOf(fun(arg0/10));    }else{        return String.valueOf(arg0);    }}

2 把金额阿拉伯数字转换为汉字表示，小数点后四舍五入保留两位。（转载）

流程图

import java.io.*;import java.lang.IllegalArgumentException;public class ConvertNum{    /** * 把金额阿拉伯数字转换为汉字表示，小数点后四舍五入保留两位     * 还有一种方法可以在转换的过程中不考虑连续0的情况，然后对最终的结果进行一次遍历合并连续的零 */    public static String [] ChineseNum = new String[]{"零","壹","贰","叁","肆","伍","陆","柒","捌","玖"};    public static String NumToChinese(double num){    if(num > 99999999999999.99 || num < -99999999999999.99)throw new IllegalArgumentException("参数值超出允许范围 (-99999999999999.99 ～ 99999999999999.99)！");        boolean negative = false;//正负标号        if(num<0){            negative = true;            num = num*(-1);        }        long temp = Math.round(num*100);        int numFen=(int)(temp%10);//分        temp=temp/10;        int numJiao = (int)(temp%10);//角        temp=temp/10;        //此时temp只包含整数部分        int [] parts =new int[20];//将金额整数部分分为在0-9999之间数的各个部分        int numParts = 0;//记录把原来金额整数部分分割为几个部分         for(int i=0;;i++){            if(temp == 0)                break;            int part = (int)(temp%10000);            parts[i] =part;            temp = temp/10000;            numParts++;        }        boolean beforeWanIsZero = true;//标志位，记录万的下一级是否为0        String chineseStr = "";        for(int i=0;i<numParts;i++){            String partChinese = partConvert(parts[i]);            if(i%2==0){//前四位，第一部分                if("".equals(partChinese))                    beforeWanIsZero = true;                else                    beforeWanIsZero = false;            }            if(i!=0){                if(i%2==0)//高9位，亿的部分                    chineseStr = "亿"+chineseStr;                else{//高5位，万的部分                    if("".equals(partChinese)&&!beforeWanIsZero)// 如果“万”对应的 part 为 0，而“万”下面一级不为 0，则不加“万”，而加“零”                        chineseStr = "零"+chineseStr;                    else{                        if(parts[i-1]<1000&&parts[i-1]>0)//如果万的部分不为0，而万前面的部分小于1000大于0，则万后面应该跟零                            chineseStr = "零"+chineseStr;                        chineseStr = "万"+chineseStr;                    }                }            }            chineseStr = partChinese + chineseStr;        }        if("".equals(chineseStr))//整数部分为0，则表示为零元            chineseStr = ChineseNum[0];        else if(negative)//整数部分部位0，但是为负数            chineseStr = "负" +chineseStr;        chineseStr = chineseStr + "元";        if(numFen==0&&numJiao==0){            chineseStr = chineseStr +"整";        }        else if(numFen==0){//0分            chineseStr = chineseStr +ChineseNum[numJiao] + "角";        }        else{            if(numJiao==0)                chineseStr = chineseStr + "零" + ChineseNum[numFen] + "分";elsechineseStr = chineseStr + ChineseNum[numJiao] + "角" + ChineseNum[numFen] + "分";        }        return chineseStr;    }    //转换拆分后的每个部分，0-9999之间    public static String partConvert(int partNum){        if(partNum<0||partNum>10000){            throw new IllegalArgumentException("参数必须是大于等于0或小于10000的整数");        }        String [] units = new String[]{"","拾","佰","仟"};        int temp = partNum;        String partResult = new Integer(partNum).toString();        int partResultLength = partResult.length();        boolean lastIsZero = true;//记录上一位是否为0        String chineseStr = "";        for(int i=0;i<partResultLength;i++){            if(temp == 0)//高位无数字                break;            int digit = temp%10;            if(digit == 0){                if(!lastIsZero)//如果前一个数字不是0则在当前汉字串前加零                    chineseStr = "零"+chineseStr;                lastIsZero = true;            }            else{                chineseStr = ChineseNum[digit] + units[i] +chineseStr;                lastIsZero = false;            }            temp =temp/10;        }        return chineseStr;      }    public static void main(String args []){            double num = 0;            System.out.println("请输入金额数字,-1退出");            num = getInputNum(num);            while(num!=-1){                System.out.println(num+NumToChinese(num));                num = getInputNum(num);            }            System.out.println("其他测试：");            System.out.println("100120: " + NumToChinese(100120));            System.out.println("25000000000005.999: " + NumToChinese(25000000000005.999));System.out.println("45689263.626: " + NumToChinese(45689263.626));System.out.println("0.69457: " + NumToChinese(0.69457));System.out.println("253.0: " + NumToChinese(253.0));System.out.println("0: " + NumToChinese(0));    }    private static double getInputNum(double num) {        try{        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));        num = Double.parseDouble(br.readLine());        }catch(IOException e){            System.out.println(e.toString());        }        return num;    }}

容易混淆的地方

需要注意的地方

6/3/2015 4:42:04 PM

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