两道算法题

 

1. 字符串截取，输入为一个字符串和一个数字，但是如果遇到汉字不能只截取半个汉字。

 

package cn.lifx.test;

public class GetNBitChar
{
    public static void main(String[] args)
    {
        String str1 = "中abc国人def伟大";

        GetNBitChar test = new GetNBitChar();

        String str2 = test.getStr(str1, 1);
        System.out.println(str2);

        str2 = test.getStr(str1, 4);
        System.out.println(str2);

        str2 = test.getStr(str1, 6);
        System.out.println(str2);

        str2 = test.getStr(str1, 8);
        System.out.println(str2);

        str2 = test.getChineseChars(str1);
        System.out.println(str2);
    }

    //获取前n个字节
    public String getStr(String str, int n)
    {
        String temp = "";

        int count = 0;
        int index = 1;

        while(count < n)
        {
            if(str.substring(index-1, index).getBytes().length == 1)
            {
                count++;
            }
            else
            {
                count = count + 2;
            }

            index++;
        }

        temp = str.substring(0, index-1);

        return temp;
    }

    //获得所有汉字
    public String getChineseChars(String str)
    {
        String temp = "";
        StringBuffer sb = new StringBuffer();

        for(int i=1; i<=str.length(); i++)
        {
            temp = str.substring(i-1, i);
            if(temp.getBytes().length == 2)
            {
                sb.append(temp);
            }
        }

        return sb.toString();
    }
}

package cn.lifx.test;

public class GetNBitChar 
{
	public static void main(String[] args)
	{
		String str1 = "中abc国人def伟大";
		
		GetNBitChar test = new GetNBitChar();
		
		String str2 = test.getStr(str1, 1);
		System.out.println(str2);
		
		str2 = test.getStr(str1, 4);
		System.out.println(str2);
		
		str2 = test.getStr(str1, 6);
		System.out.println(str2);
		
		str2 = test.getStr(str1, 8);
		System.out.println(str2);
		
		str2 = test.getChineseChars(str1);
		System.out.println(str2);
	}
	
	//获取前n个字节
	public String getStr(String str, int n)
	{
		String temp = "";
		
		int count = 0;
		int index = 1;
		
		while(count < n)
		{
			if(str.substring(index-1, index).getBytes().length == 1)
			{
				count++;
			}
			else
			{
				count = count + 2;
			}
			
			index++;
		}
		
		temp = str.substring(0, index-1);
		
		return temp;
	}
	
	//获得所有汉字
	public String getChineseChars(String str)
	{
		String temp = "";
		StringBuffer sb = new StringBuffer();
		
		for(int i=1; i<=str.length(); i++)
		{
			temp = str.substring(i-1, i);
			if(temp.getBytes().length == 2)
			{
				sb.append(temp);
			}
		}
		
		return sb.toString();
	}
}

 

 

2. 一个数组有2n个整数，其中有n个奇数，n个偶数，要求把奇数放在奇数位置，偶数放在偶数位置。

 

package cn.lifx.test;

public class SortOddAndEvenNum
{
    public static void main(String[] args)
    {
        int[] arr = {2, 3, 4, 6, 8, 5, 7, 9};

        SortOddAndEvenNum sort = new SortOddAndEvenNum();

        sort.Display(arr, "Before:");

        sort.Sort(arr);

        sort.Display(arr, "After:");
    }

    public void Sort(int[] arr)
    {
        int index1 = 0;
        int index2 = 1;

        int temp = 0;
        int n = arr.length;

        while(index1 < n && index2 < n)
        {
            while(arr[index1] % 2 != 0)
            {
                index1 += 2;
            }

            while(arr[index2] % 2 == 0)
            {
                index2 += 2;
            }

            temp = arr[index1];
            arr[index1] = arr[index2];
            arr[index2] = temp;

            index1 += 2;
            index2 += 2;
        }
    }

    public void Display(int[] arr, String str)
    {
        System.out.println(str);
        for(int i=0; i<arr.length; i++)
        {
            System.out.print(arr[i] + " ");
        }
        System.out.println();
    }
}