替换空格

题目描述：请实现一个函数，将一个字符串中的每个空格替换成“%20”。例如，当字符串为We Are Happy.则经过替换之后的字符串为We%20Are%20Happy。

实现语言：Java

public class Solution {
    public String replaceSpace(StringBuffer str) {
    	char[] sc=str.toString().toCharArray();
        int replaceLen=0;
        for(int i=0;i<sc.length;++i){
            if(sc[i]==' '){
                ++replaceLen;
            }
        }
        char[] res=new char[sc.length+2*replaceLen];
        int oldLen=sc.length-1;
        int newLen=res.length-1;
        while(newLen>=0){
            if(sc[oldLen]==' '){
                res[newLen--]='0';
                res[newLen--]='2';
                res[newLen--]='%';
            }else{
                res[newLen--]=sc[oldLen];
            }
            --oldLen;
        }
        return String.valueOf(res);
    }
}

 实现语言：Java

public class Solution {
    public String replaceSpace(StringBuffer str) {
    	StringBuffer sb=new StringBuffer();
        char[] sc=str.toString().toCharArray();
        for(int i=0;i<sc.length;++i){
            if(sc[i]==' '){
                sb.append("%20");
            }else{
                sb.append(sc[i]);
            }
        }
        return sb.toString();
    }
}

 实现语言：python

# -*- coding:utf-8 -*-
class Solution:
    # s 源字符串
    def replaceSpace(self, s):
        # write code here
        l=list(s)
        r=['%20' if ss==' ' else ss for ss in l]
        return ''.join(r)