《剑指Offer》面试题4：替换空格

《剑指Offer》面试题4：替换空格

题目描述

    请实现一个函数，把字符串中的每个空格替换成“%20”。例如输入“We are happy.”，则输出“We%20are%20happy.”。

解题思路

测试用例

代码

/*《剑指Offer——名企面试官精讲典型编程题》代码
 著作权所有者：何海涛*/

#include "stdio.h"
#include <string>

/*length 为字符数组string的总容量*/
void ReplaceBlank(char string[], int length)
{
	if (string == NULL && length <= 0)
		return;

	/*originalLength 为字符串string的实际长度*/
	int originalLength = 0;
	int numberOfBlank = 0;
	int i = 0;
	while (string[i] != '\0')
	{
		++originalLength;

		if (string[i] == ' ')
			++numberOfBlank;

		++i;
	}

	/*newLength 为把空格替换成'%20'之后的长度*/
	int newLength = originalLength + numberOfBlank * 2;
	if (newLength > length)
		return;

	int indexOfOriginal = originalLength;
	int indexOfNew = newLength;
	while (indexOfOriginal >= 0 && indexOfNew > indexOfOriginal)
	{
		if (string[indexOfOriginal] == ' ')
		{
			string[indexOfNew--] = '0';
			string[indexOfNew--] = '2';
			string[indexOfNew--] = '%';
		}
		else
		{
			string[indexOfNew--] = string[indexOfOriginal];
		}

		--indexOfOriginal;
	}
}

void Test(char* testName, char string[], int length, char expected[])
{
	if (testName != NULL)
		printf("%s begins: ", testName);

	ReplaceBlank(string, length);

	if (expected == NULL && string == NULL)
		printf("passed.\n");
	else if (expected == NULL && string != NULL)
		printf("failed.\n");
	else if (strcmp(string, expected) == 0)
		printf("passed.\n");
	else
		printf("failed.\n");
}

// 空格在句子中间
void Test1()
{
	const int length = 100;

	char string[length] = "hello world";
	Test("Test1", string, length, "hello%20world");
}

// 空格在句子开头
void Test2()
{
	const int length = 100;

	char string[length] = " helloworld";
	Test("Test2", string, length, "%20helloworld");
}

// 空格在句子末尾
void Test3()
{
	const int length = 100;

	char string[length] = "helloworld ";
	Test("Test3", string, length, "helloworld%20");
}

// 连续有两个空格
void Test4()
{
	const int length = 100;

	char string[length] = "hello  world";
	Test("Test4", string, length, "hello%20%20world");
}

// 传入NULL
void Test5()
{
	Test("Test5", NULL, 0, NULL);
}

// 传入内容为空的字符串
void Test6()
{
	const int length = 100;

	char string[length] = "";
	Test("Test6", string, length, "");
}

//传入内容为一个空格的字符串
void Test7()
{
	const int length = 100;

	char string[length] = " ";
	Test("Test7", string, length, "%20");
}

// 传入的字符串没有空格
void Test8()
{
	const int length = 100;

	char string[length] = "helloworld";
	Test("Test8", string, length, "helloworld");
}

// 传入的字符串全是空格
void Test9()
{
	const int length = 100;

	char string[length] = "   ";
	Test("Test9", string, length, "%20%20%20");
}

int main()
{
	Test1();
	Test2();
	Test3();
	Test4();
	Test5();
	Test6();
	Test7();
	Test8();
	Test9();
	system("pause");
	return 0;
}

相关题目

    有两个排序数组A1和A2，内存在A1的末尾有足够多的空余空间容纳A2，实现一个函数，把A2中的所有数字插入到A1中并且所有的数字是排序的。

#include <iostream>
using namespace std;
void MerageArray(int *a1, int *a2, int a1Length, int a2Length, int a1Volume)
{
	//两个排序的数组a1和a2，它们的实际长度a1Length和a2Length，a1Volume为a1的总容量
	int merageLength = a1Length + a2Length;  //合并两个数组后的实际长度

	//边界检查  
	if (!a1 || !a2 || merageLength > a1Volume ||
		a1Length <= 0 || a2Length <= 0)
	{
		return;
	}

	int index = merageLength - 1; //用来指向a1或a2中元素要被复制到的位置  

	int a1Index = a1Length - 1; //指向a1中要复制元素的位置  

	int a2Index = a2Length - 1;//指向a2中要复制元素的位置  

	while (index >= 0 && a1Index >= 0 && a2Index >= 0)
	{
		//将两个数组中较大的元素复制
		if (a1[a1Index] > a2[a2Index])
		{
			a1[index] = a1[a1Index];         

			a1Index--;
		}
		else
		{
			a1[index] = a2[a2Index];

			a2Index--;
		}

		index--;
	}

	//当数组a1中的元素已复制完，但数组a2仍有元素，则将其依次复制到a1中
	while (index >= 0 && a2Index >= 0)
	{
		a1[index] = a2[a2Index];

		index--;

		a2Index--;
	}
}

int main()
{
	int a[10] = { 12, 13, 14, 15 };
	int b[6] = { 1, 4, 5, 9, 10 };
	int len1 = 4;
	int len2 = 5;
	MerageArray(a, b,len1,len2,10);
	for (int i = 0; i<len1 + len2; i++)
	{
		cout << a[i] << " ";
	}
	system("pause");
	return 0;
}