自己写的三角形，请大佬们看看，给点意见吧

#include"stdio.h"
#include"stdlib.h"
int main()
{
    int a=1;              
    int b=1;
    system("color 0A");            
    while(a<=20)
    {
        b=1;              
        while(b<=a)         
        {
            printf("*");
            sleep(50);
            b=b+1;
        }
        printf("\n");
        sleep(50);
        a=a+1;
    }
    return 0;
}