動機
就是算
Problem
Write an algorithm to determine if a number n
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.
- 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.
Return true
if n
is a happy number, and false
if not.
Example 1:
Input: n = 19Output: trueExplanation:12 + 92 = 8282 + 22 = 6862 + 82 = 10012 + 02 + 02 = 1
Example 2:
Input: n = 2Output: false
Constraints:
1 <= n <= 231 - 1
Sol
def happy(n):
tmp = [int(x)*int(x) for x in list(str(n))]
return sum(tmp)
class Solution:
def isHappy(self, n: int) -> bool:
tbl = set()
while n not in tbl and n != 1:
tbl.add(n)
n = happy(n)
return (n == 1)