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@siqin
Forked from Ninputer/RemoveMultipleSpaces.cs
Created April 1, 2012 14:49
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模拟微面试之去空格
//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("baseStr");
}
int writeCursor = 0;
bool isLastCharSpace = false;
for (int i = 0; i < baseStr.Length; i++)
{
char current = baseStr[i];
if (current == ' ')
{
if (!isLastCharSpace)
{
isLastCharSpace = true;
baseStr[writeCursor++] = current;
}
}
else
{
isLastCharSpace = false;
baseStr[writeCursor++] = current;
}
}
return writeCursor;
}
}
//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));
}
}
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siqin commented Apr 1, 2012

这道题让我想到的是编译器词法分析的状态转换,貌似出题者Ninputer对这方面颇有研究。
复制过来,突然发现RemoveMultipleSpaces函数实现补全了,之前是//TODO

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