题解

#include<bits/stdc++.h>
using namespace std;
int main(){
    int a;
    cin>>a;
    for(int i=1;i<=a;i++){
        for(int j=1;j<=i;j++)
            cout<<"* ";
        cout<<endl;
    }
    for(int i=1;i<=a+1;i++)
        cout<<"* ";
    cout<<endl;
    for(int i=a;i>=0;i--){
        for(int j=1;j<=i;j++)
            cout<<"* ";
        cout<<endl;
    }
    return 0;
}