06 java 基础：java 循环 递归

1 递归实现 1 + 2 +3 +4 +5 + .... +100

   public static int  addSum(int num){

       if(num == 1)
        return 1;
       return num + addSum(num-1);

   }

2 递归实现阶乘  1！+2！+3！+...+ 100!

          public static int factorial(int num){

            if(num ==1)
            return 1;
            else
            retun num *factorial(num-1);

           }

3 循环实现乘法表

       public static void  printMult(){

          for(int i=1 ;i<=9;i++){
              for(int j=1;j<=i;j++){
               System.out.print(i+"*"+j+"="+(i*j)+"\t");
              }
              System.out.println();
           }

    }