Leetcode#202Happy Number
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
问题分析，难点如何识别出计算链条出现loop，此处采用的hash的方法
public class Solution {
public boolean isHappy(int n) {
Map<Integer,Integer> p=new HashMap<Integer,Integer>();
int m=n;
int sm=0;
while(m>1)
{
sm=m;
int x=0;
while(m>0)
{
x=x+(m%10)*(m%10);
m=m/10;
}
if(p.get(x)!=null)
return false;
else
{
p.put(x,1);
m=x;
}
}
return true;
}
}
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