作者: | 来源:互联网 | 2023-09-02 19:26
Writeanalgorithmtodetermineifanumberis happy.Ahappynumberisanumberdefinedbythefollowingpro
Write an algorithm to determine if a number is happy.
A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers.
Example
19 is a happy number
1^2 + 9^2 = 82 8^2 + 2^2 = 68 6^2 + 8^2 = 100 1^2 + 0^2 + 0^2 = 1
这道题的做法是就是把一个正数不断求各个数位的平方和,如果得到了1,就返回true,否则把结果存在一个set里,如果一旦出现重复的数,说明不能得到1,所以不是happy number
public class Solution {
/**
* @param n an integer
* @return true if this is a happy number or false
*/
public boolean isHappy(int n) {
// Write your code here
if(n <= 0)
return false;
if(n == 1)
return true;
HashSet set = new HashSet();
int num = n;
while(!set.contains(num)){
set.add(num);
int next = 0;
while(num > 0){
next += (num % 10) * (num % 10);
num /= 10;
}
if(next == 1)
return true;
else
num = next;
}
return false;
}
}