java编程：输出倒等腰三角形

package d;

import java.util.Scanner;

public class DD {

public static void main(String[] args) {

Scanner input=new Scanner(System.in);

System.out.println("请输入n");

int n=input.nextInt();

for(int a=n;a>=1;a--){

for(int b=a;b<=n;b++){

System.out.print(" ");

}

for(int c=1;c<=2*a-1;c++){

System.out.print("X");

}

System.out.println();

}

}

}