LeetCode Happy Number
Problem
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
1^2 + 9^2 = 82
8^2 + 2^2 = 68
6^2 + 8^2 = 100
1^2 + 0^2 + 0^2 = 1
Python3
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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
#
# 1^2 + 9^2 = 82
# 8^2 + 2^2 = 68
# 6^2 + 8^2 = 100
# 1^2 + 0^2 + 0^2 = 1
class Solution:
def isHappy(self, n):
"""
:type n: int
:rtype: bool
"""
temp_result = {}
return self.docharge(n, temp_result)
def docharge(self, n, temp_result):
if temp_result.get(n) is not None:
return False
temp_result[n] = n
cur_sum = 0
while n > 0:
cur_num = n % 10
cur_sum += cur_num ** 2
n //= 10
if cur_sum == 1:
return True
else:
return self.docharge(cur_sum, temp_result)
solution = Solution()
print(solution.isHappy(19))
print(solution.isHappy(23))
print(solution.isHappy(22))
分析
根据题意，直接计算即可。
所有代码已上传至Github：https://github.com/lihongzheshuai/yummy-code
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