LeetCode 202-Happy Number-优快云博客

本文链接：https://blog.youkuaiyun.com/keitho00/article/details/45217607

本文介绍了一个算法用于判断一个数字是否为'快乐数'，通过不断替换数字为各位数字的平方和，直到数字等于1或陷入循环。以19为例，进行步骤计算验证其快乐性。

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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
题目解析：该题的关键点在于处理循环数的时候不能一直做循环

代码：

public class Solution {
    	public boolean isHappy(int n) {

		int temp=n;
		int tempTo=0;
		for(int i=0;i<100;i++){

			tempTo=func(temp);
//			System.out.println(temp);
//			System.out.println(tempTo);
			if(temp==tempTo){
				if(temp==1) return true;
				else return false;
			}
			temp=tempTo;	
		}
		return false;
		
		
		
	}
	public int func(int n){
		String s=String.valueOf(n);
		char[] ch=s.toCharArray();
		int result=0;
		for(int i=0;i<ch.length;i++){
//System.out.println(Integer.valueOf(ch[i]+""));
			result=result+Integer.valueOf(ch[i]+"")*Integer.valueOf(ch[i]+"");
		}
//		System.out.println("result:"+result);
		return result;
	}
}