【leetcode】507. Perfect Number

problem

507. Perfect Number

solution:

/*
class Solution {
public:
    bool checkPerfectNumber(int num) {
        int sum = 1;
        for(int i=2; i*i<=num; i++)
        {
            if(num%i==0) sum += i + (num/i == i) ? 0 : num/i; //
        }
        return (sum == num) && (num!=1);
    }

};

*/
class Solution {
public:
    bool checkPerfectNumber(int num) {
        int sum = 1;
        for (int i = 2; i * i <= num; ++i) {
            if (num % i == 0) {
                sum += i + (num / i == i ? 0 : num / i);
            }
        }
        return num != 1 && sum == num;
    }
};

奇怪！！！为什么上边的solution不能accept，改的是一样的哈。。。反正宝宝是没有看出差别在哪里。。。

solution2: 枚举法，哈哈哈

class Solution {
public:
    bool checkPerfectNumber(int num) {
        return num==6 || num==28 || num==496 || num==8128 || num== 33550336;
    }
};

参考

1. Leetcode_507. Perfect Number;

完