[程序人生]: 反转一个句子

题目：

反转一个句子，要求句子中的每个单子都被反转，但单词本身不被反转

如：I am a Boy! 反转为：Boy! a am I

思路：左旋转处理

1. 将整个句子的所有字符统一反转

2. 根据空格，阶段单词，再反转每一个单词

代码：

public static String ReversalString(String StrInput){

/*
char[] charTemp = StrInput.toCharArray();

int iFlagBegin = 0;
int iFlagEnd = charTemp.length-1;

while(iFlagBegin < iFlagEnd){
char Temp = charTemp[iFlagBegin];
charTemp[iFlagBegin] = charTemp[iFlagEnd];
charTemp[iFlagEnd] = Temp;

iFlagBegin++;
iFlagEnd--;
}

return String.valueOf(charTemp);
*/
String strResult = "";

for(int i =0;i<StrInput.length();i++ ){
strResult =StrInput.substring(i,i+1) + strResult;
}
return strResult;
}

public static String ReversalSentence(String Initial){
String strResult = "";
String strReversalAll = ReversalString(Initial);

int iFlag = 0;
for(int i = 0; i < strReversalAll.length(); i++){
if(strReversalAll.substring(i, i+1).equals(" ")){
if(i >= iFlag){
strResult += ReversalString(strReversalAll.substring(iFlag,i)) + " ";
iFlag = i+1;
}
}

if(i == strReversalAll.length() -1){
if(strReversalAll.substring(i,i+1).equals(" ")){
strResult = strResult.substring(0, strResult.length()-1);
}
else{
strResult += ReversalString(strReversalAll.substring(iFlag,i+1));
}
}
}

return strResult;
}

分析：注意翻转字符串的函数，用注释中的写法高效！

思路二：查找空格，直接按照单词为集合反转

public static String ReversalSentence(String Initial){

String strResult ="";
int iFlag = 0;
for(int i = 0; i < Initial.length(); i++){
if(i == Initial.length() -1){
strResult = Initial.substring(iFlag,i+1) + " "  + strResult ;
}

if(Initial.substring(i, i+1).equals(" ")){
if(i >= iFlag){
if(iFlag == 0){
strResult = Initial.substring(iFlag,i) + strResult;
}else{
strResult = Initial.substring(iFlag,i) + " " + strResult;
}

iFlag = i+1;
}
}
}

return strResult;
}