reverse
可以翻轉陣列
#include<bits/stdc++.h>
using namespace std;
int main()
{
string a;
cin>>a;
char x[a.length()];
for(long long int i=0;i<a.length();i++) x[i]=a[i];
reverse(x,x+a.length());
int k=0;
for(long long int i=0;i<a.length();i++)
{
if(k==0 and i==a.length()-1) cout<<'0';
else if(x[i]=='0' and k==0) continue;
else
{
cout<<x[i];k=1;
}
}
cout<<'\n';
}