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(); } }