We define the Perfect Number is a positive integer that is equal to the sum of all its positive divisors except itself.
Now, given an integer n, write a function that returns true when it is a perfect number and false when it is not.
Example:
Input: 28 Output: True Explanation: 28 = 1 + 2 + 4 + 7 + 14
Note: The input number n will not exceed 100,000,000. (1e8)
A:
------------------------------------注意要排除 1 , except itself ---------
class Solution { public: bool checkPerfectNumber(int num) { if(num<=1) return false; int curSum = 1; for(int i=2;i<=num/2;++i) { if(num %i ==0) curSum += i; } return curSum == num; } };
No comments:
Post a Comment