面试杂题（六）替换空格

输入：we are happy 输出we%20are%20happy

要求是原位移动，不申请新的空间

void replaceSpace(char *pStr,int nSize)
{
	int nLen=strlen(pStr);
	int nCnt=0;
	for(int i=0;i<nLen;i++)
	{
		if (pStr[i]==' ')
		{
			nCnt++;
		}
	}
	int nLenObj=nLen+2*nCnt;
	if (nSize<nLenObj+1)
	{	
		cout<<"空间不足"<<endl;
		return;
	}
	for (int i=nLen-1;i>=0;--i)
	{	
		if (pStr[i]==' ')
 		{
 			nCnt--;
			pStr[i+nCnt*2]='%';
			pStr[i+nCnt*2+1]='2';
			pStr[i+nCnt*2+2]='0';
 			continue; 
 		}
 		pStr[i+nCnt*2]=pStr[i];
	}
	for (int i=0;i<nLenObj;i++)
	{
		cout<<pStr[i];
	}
	cout<<endl;
}