劍指 Offer 05. 替換空格

請實現(xiàn)一個函數(shù)，把字符串?s?中的每個空格替換成"%20"。

?

示例 1：

輸入：s = "We are happy."輸出："We%20are%20happy."

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限制：

0 <= s 的長度 <= 10000

通過次數(shù)635,932提交次數(shù)843,438

第一種對法：

class?Solution?{

public:

????string?replaceSpace(string?s)?{

????????string?ans;

????????for(auto?a:s){

????????????if(a=='?'){

????????????????ans+="%20";

????????????}else{

????????????????ans+=a;

????????????}

????????}

????????return?ans;

????}

};

第二種對法：

class?Solution?{

public:

????string?replaceSpace(string?s)?{

????????int?count?=?0;

????????int?sOldSize?=?s.size();

????????for(int?i=0;i<s.size();i++){

????????????if(s[i]=='?'){

????????????????count++;

????????????}

????????}

????????s.resize(s.size()+count*2);

????????int?sNewSize?=?s.size();

????????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;

????}

};