leetcode-202-Happy-Number

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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

$1^2 + 9^2 = 82$
$8^2 + 2^2 = 68$
$6^2 + 8^2 = 100$
$1^2 + 0^2 + 0^2 = 1$

分析

meh

解决方案1(C)

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bool isHappy(int n) {
    if(n <= 0){
        return false;
    }
    while(n != 1){
        int num = n;
        int sum = 0;
        while(num!=0){
            sum = sum + (num%10)*(num%10);
            num = num / 10;
        }
        n = sum;
        if(n < 10 && n != 1){
            return false;
        }
    }
    return true;
}

解决方案2(Python)

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class Solution(object):
    def isHappy(self, n):
        """
        :type n: int
        :rtype: bool
        """
        if(n <= 0):
            return
        while n != 1:
            num = n
            sum = 0
            while num != 0:
                sum += (num%10) * (num%10)
                num /= 10
            n = sum
            if n<10 and n!=1:
                return False
        return True

解决方案3（Golang）

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func isHappy(n int) bool {
    intSeenMap := map[int]bool{}
    for ; n != 1 && !intSeenMap[n]; n, intSeenMap[n] = next(n), true {
        
    }
    return n == 1
}

func next(n int) int {
    result := 0
    for n > 0 {
        result += (n%10) * (n%10)
        n = n / 10
    }
    return result
}

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