leetcode 202. Happy Number

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202. Happy Number

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Total Accepted: 56706 Total Submissions: 158441 Difficulty: Easy

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

Credits:
Special thanks to @mithmatt and @ts for adding this problem and creating all test cases.

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按公式计算，判断一个数是不是happy number

class Solution {
public:
bool isHappy(int n) {
if(n < 0) return false;
map<int,int> mp;
while(n != 1){
if(mp
== 1) return false;
mp
= 1;
n = calculate(n);
}
return true;
}
int calculate(int n)
{
int ret = 0;
int temp = 0;
while(n){
temp = n % 10;
ret += (temp * temp);
n /= 10;
}
return ret;
}
};