#include<bits/stdc++.h>
#define yy return 0;
using namespace std;
int main() {
    cout<<"  *"<<endl;
    cout<<" ***"<<endl;
    cout<<"*****"<<endl;
    cout<<" ***"<<endl;
    cout<<"  *"<<endl;
    yy
}

#include<bits/stdc++.h>
using namespace std;
int main(){
	cout<<R"(  *
 ***
*****
 ***
  *

)";
	return 0;
}

仅供参考

#include <iostream>
using namespace std;
int main() {
	cout << "  *\n ***\n*****\n ***\n  *" ;
	return 0;
}

#include <iostream>
using namespace std;
int main(){
	cout<<"  *\n ***\n*****\n ***\n  *";
	return 0;
}

水题

#include<bits/stdc++.h>
using namespace std;
int main(){
    cout<<"  *"<<endl;
    cout<<" ***"<<endl;
    cout<<"*****"<<endl;
    cout<<" ***"<<endl;
    cout<<"  *"<<endl;
    return 0;
}

#include<bits/stdc++.h> using namespace std; int main() { cout<<" *"<<endl; cout<<" "<<endl; cout<<"**"<<endl; cout<<" ***"<<endl; cout<<" *"<<endl; return 0; }