答案

#include <bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin >> n;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= n - i; j++){
        	cout << " ";
        }
        if(i == 1){
            cout << "*";
        }else{
            cout << "*";
            for(int j = 1; j <= (i - 1) * 2 - 1; j++){
                cout << " ";
            }
            cout << "*";
        }
        cout << endl;
    }
    for(int i = n - 1; i >= 1; i--){
        for(int j = 1; j <= n - i; j++){
            cout << " ";
        }
        if(i == 1){
            cout << "*";
        }else{
            cout << "*";
            for(int j = 1; j <= (i - 1) * 2 - 1; j++){
                cout << " ";
            }
            cout << "*";
        }
        cout << endl;
	}
    return 0;
}