剑指 Offer 05：替换空格

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

class Solution:
    def replaceSpace(self, s: str) -> str:
    return s.replace(" ","%20")

class Solution:
    def replaceSpace(self, s: str) -> str:
      t = s.split(" ")
        return "%20".join(t)

class Solution:
    def replaceSpace(self, s: str) -> str:
        res = ""
        for c in s:
            if c!=" ":
                res+=c
            else:
                res+="%20"
        return res

class Solution {
public:
    string replaceSpace(string s) {
        string res;
        for(char c:s){
            if(c==' ') res+="%20";
            else res+=c;
        }
        return res;
    }
};

class Solution {
public:
    string replaceSpace(string s) {
        int count = 0; // 统计空格的个数
        int sOldSize = s.size();
        for (int i = 0; i < s.size(); i++) {
            if (s[i] == ' ') {
                count++;
            }
        }
        // 扩充字符串s的大小，也就是每个空格替换成"%20"之后的大小
        s.resize(s.size() + count * 2);
        int sNewSize = s.size();
        // 从后先前将空格替换为"%20"
        for (int i = sNewSize - 1, j = sOldSize - 1; j < i; i--, j--) {
            if (s[j] != ' ') {
                s[i] = s[j];
            } else {
                s[i] = '0';
                s[i - 1] = '2';
                s[i - 2] = '%';
                i -= 2;
            }
        }
        return s;
    }
};

class Solution {
    public String replaceSpace(String s) {
        StringBuilder res=new StringBuilder();
        for(Character c:s.toCharArray()){
            if(c==' ') res.append("%20");
            else res.append(c);
        }
        return res.toString();
    }
}