剑指 Offer 05. 替换空格

剑指 Offer 05. 替换空格

请实现一个函数，把字符串 s 中的每个空格替换成"%20"。

 

示例 1：

输入：s = "We are happy."
输出："We%20are%20happy."
 

限制：

0 <= s 的长度 <= 10000

 

Python实现非常简单，直接调用函数即可

 

class Solution(object):
    def replaceSpace(self, s):
        """
        :type s: str
        :rtype: str
        """
        return s.replace(" ","%20")

 

C++ 实现版本1

class Solution {
public:
	string replaceSpace(string s) {
		if (s.length()==0) {
			return s;
		}

		int originalLength = s.size()-1;
		int numberOfBlank = 0;
		int i = 0;

		for (auto c : s) {
			if (c == ' ') ++numberOfBlank;;
		}

		
		/*newLength 为把空格替换为'/20'之后的长度*/

		int newLength = originalLength + numberOfBlank * 2;
		s += string(numberOfBlank * 2, ' ');
		int indexOfOriginal = originalLength;

		int indexOfNew = newLength;

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

			indexOfOriginal--;
		}
		return s;
	}
};

C++实现版本2

 

class Solution {
public:
	string replaceSpace(string s) {
		string res;

		for (auto c : s) {
			if (c == ' ')
				res += "%20";
			else
				res += c;
		}
		return res;
	}
};