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:
Input: 19
Output: true
Explanation:
1^2 + 9^2 = 82
8^2 + 2^2 = 68
6^2 + 8^2 = 100
1^2 + 0^2 + 0^2 = 1
代码实现
function isHappy(data, set = new Set()){
let arr = data.toString().split("")
let ans = 0
for (let index = 0; index < arr.length; index++) {
ans += Math.pow(arr[index],2)
}
if(arr.length === 1){
if(set.has(arr[0])){
return false;
}
set.add(arr[0])
if(arr[0] === '1'){
return true
}else{
return isHappy(Math.pow(arr[0],2),set)
}
}else{
return isHappy(ans,set)
}
}