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| // @Title: 完美数 (Perfect Number)
// @Author: 15816537946@163.com
// @Date: 2021-12-31 15:49:38
// @Runtime: 0 ms
// @Memory: 5.3 MB
bool checkPerfectNumber(int num) {
if (num == 1 || num < 0)
return false;
int i = 2;
int res = 1;
for (; i < sqrt(num); i++) {
if (num % i == 0)
res += i + num / i;
}
/*
if ((int(sqrt(num)) >= i) && (num % i == 0))
res += i;
*/
return res == num;
}
/*
class Solution {
public:
bool checkPerfectNumber(int num) {
if ((num == 1) || (num < 0)) // edge cases - number is negitive or 1
return false;
int i = 2;
int res = 1;
for (; i<sqrt(num); i++)
{
if (num % i == 0)
res += i + num/i;
}
if ((int(sqrt(num)) >= i ) && (num % i == 0)) // edge case - number has
a whole sqrt res += i;
return res == num;
}
};
*/
|