Happy Number
Total Accepted:11462 Total Submissions: 35743
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
- 12 + 92 = 82
- 82 + 22 = 68
- 62 + 82 = 100
- 12 + 02 + 02 = 1
Hide tags HashTable Math 思路：多次使用自定義的求平方和函數， 關鍵在于分離給定數的各個位置上的數，通常使用 s=n%10 ,n=n/10 方法進行數字處理
代碼如下：
public boolean isHappy(int n)
{
int sum=powsum(n);
while(sum>9)
{
//不滿足條件時，多次調用
sum=powsum(sum);
}
if(sum==1)
{
return true;
}
return false;
}
private int powsum(int n)
{
int sum=0;
//使用while循環
while(n!=0)
{
//分離數各個位置上的數
int s=n%10;
//求平方和，其中Math.pow(x,y) 意思為x的y次幂
sum=(int) (sum+Math.pow(s, 2));
n=n/10;
}
return sum;
}
補充：可以使用HashTable 對每一次powsum傳回的值進行記錄，如果HashTable中已經有記錄，則說明進入了死循環，直接傳回false,