1 题目描述

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

链接地址:https://leetcode.com/problems/happy-number/

2 解决方案

java代码如下:

public class Solution {
public boolean isHappy(int n) {
int result = 0;
ArrayList<Integer> list = new ArrayList<Integer>();
boolean isLucky = false;
if (n <= 0) {
return isLucky;
}
while (true) {
int sum = 0;
int num = n;
while (num > 0) {
int temp = num%10;
num = (num -temp)/ 10;
sum = sum + temp * temp ;
} result = sum; if (result ==1 ) {
isLucky = true;
break;
}
else if(list.contains(result)) {
isLucky = false;
break;
}else {
n = result;
list.add(result);
} }
return isLucky;
}
}

  

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