n<=20

C语言解答

#include <stdio.h>

int main()
{
    int i, j, n;
    scanf( "%d", &n );
    for ( i = 0; i < n; ++i ) {
        for ( j = 0; j <= i; ++j ) {
            putchar( '*' );
        }
        putchar( '\n' );
    }
}

C++解答

#include <iostream>
using namespace std;
int main()
{
	int n,i,j;
	cin>>n;
	for(i=1;i<=n;i++)
	{
		for(j=1;j<=i;j++)
		{
			cout<<'*';
		}
		cout<<endl;
	}
	return 0;
}

Java解答

import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner in=new Scanner(System.in);
        while(in.hasNext()){
            int n=in.nextInt();
            int step=1;
            for(int j=0;j<n;j++){
                for(int i=1;i<=step;i++){
                    System.out.print("*");
                }
                step++;
                System.out.println();
            }
        }
    }
}