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javascript 递归之阶乘

阶乘,即5! = 5*4*3*2*1, 先看传统的做法,利用while循环实现:

function factorial(num){  var result = num;  if(num<0){    return -1;    //负数返回-1  }  if(num == 0){    return 1;    // 0阶乘为1  }    while(num-- >2){    result = result*num;      }  return result;}

 javascript递归函数通过它调用其本身,利用递归的思路的话,阶乘的思路应该是 factorial(num)*factorial(num-1)*factorial(num-2) … factorial(0),即每次把num-1后作为参数调用自身:

function factorial2(num){  if(num <0){    return -1;  }  if(num == 0){    return 1;  }  return num*(factorial2(num-1));}

  

javascript 递归之阶乘