执行用时和内存消耗加起来绝对约等于90的

#include<iostream>
using namespace std;
int main()
{
	string a,b;
	cin>>a;
	int len=a.size();
	for(int i=len-1,j=0;j<len;i--,j++) b[j]=a[i];
	for(int i=0;i<len;i++)
	{
		if((b[i]>='x' and b[i]<='z')or(b[i]>='X' and b[i]<='Z')) b[i]=char(b[i]-23);
		else b[i]=char(b[i]+3);
	}
	for(int i=0;i<len;i++)
	{
		if(b[i]>='a' and b[i]<='z') b[i]=char(b[i]-32);
		else if(b[i]>='A' and b[i]<='Z') b[i]=char(b[i]+32);
	}
	for(int i=0;i<len;i++) cout<<b[i];
}