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_202.java
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_202.java
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package com.fishercoder.solutions;
import java.util.HashSet;
import java.util.Set;
/**
* 202. Happy 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
*/
public class _202 {
public static class Solution1 {
public boolean isHappy(int n) {
if (n == 1) {
return true;
}
Set<Integer> seen = new HashSet();
seen.add(n);
int result = 0;
while (result != 1) {
result = getResult(n);
if (seen.contains(result)) {
return false;
}
seen.add(result);
n = result;
}
return true;
}
private Integer getResult(int num) {
int result = 0;
while (num != 0) {
result += (num % 10) * (num % 10);
num /= 10;
}
return result;
}
}
}