模拟微面试之去空格

RemoveMultipleSpaces.cs

//请实现下面的函数，输入参数baseStr是一个（可以更改的）字符串，请将其中所有连续出现的多个空格都替换成一个空格，单一空格需保留。
//请直接使用baseStr的空间，如需开辟新的存储空间，不能超过o(N)（注意是小o，N是字符串的长度）。返回值是替换后的字符串的长度。
//样例代码为C#，但可以使用任何语言。如需使用任何库函数，必须同时给出库函数的实现。
class Program
{
    public static int RemoveMultipleSpaces(char[] baseStr)
    {
        if (baseStr == null)
	    throw new ArgumentNullException();

	char SPACE = ' ';
	
	int dup = 0, len = baseStr.Length;
	
	for (int i = baseStr.Length - 1; i >= 1; i--)
	{
	    if (baseStr[i] == SPACE)
	    {
	        if (baseStr[i - 1] == SPACE)
		{
		    Shift(baseStr, i, 1);
		    dup++;
		}
	    }
	}
	
	return len - dup;
    }

    private static void Shift(char[] arr,int pos, int len)
    {
	for (int i = pos; i < arr.Length; i++)
	{
	    arr[i - len] = arr[i];
	}
    }
}

//样例测试程序（请自行补充更多的测试案例）
[TestFixture]
public class ScannersTest
{
    [Test]
    public void RemoveOneInnterSpaceBlockTest()
    {
        char[] input = "abc    def".ToCharArray();

        int resultLength = Program.RemoveMultipleSpaces(input);

        Assert.AreEqual(7, resultLength);
        Assert.AreEqual("abc def", new string(input, 0, resultLength));
    }

    [Test]
    public void RemoveTwoInnterSpaceBlocksTest()
    {
        char[] input = "abc    def       ghi".ToCharArray();

        int resultLength = Program.RemoveMultipleSpaces(input);

        Assert.AreEqual(11, resultLength);
        Assert.AreEqual("abc def ghi", new string(input, 0, resultLength));
    }

    [Test]
    public void KeepSingleSpaceTest()
    {
        char[] input = " a b   d e ".ToCharArray();

        int resultLength = Program.RemoveMultipleSpaces(input);

        Assert.AreEqual(9, resultLength);
        Assert.AreEqual(" a b d e ", new string(input, 0, resultLength));
    }

    [Test]
    public void AllSpacesTest()
    {
        char[] input = "             ".ToCharArray();

        int resultLength = Program.RemoveMultipleSpaces(input);

        Assert.AreEqual(1, resultLength);
        Assert.AreEqual(" ", new string(input, 0, resultLength));
    }

    [Test]
    public void EmptyStringTest()
    {
        char[] input = "".ToCharArray();
        int resultLength = Program.RemoveMultipleSpaces(input);

        Assert.AreEqual(0, resultLength);
        Assert.AreEqual("", new string(input, 0, resultLength));
    }
}