Gym 101667D Happy Number（简单题）

Gym 101667D Happy Number

Description

Consider the following function ݂ defined for any natural number ݊:
݂ሺ݊ሻ is the number obtained by summing up the squares of the digits of ݊ in decimal (or base-ten).
If ݊ ൌ 19, for example, then ݂ሺ19ሻ ൌ 82 because 1ଶ ൅ 9ଶ ൌ 82.
Repeatedly applying this function ݂, some natural numbers eventually become 1. Such numbers are called happy numbers. For example, 19 is a happy number, because repeatedly applying function ݂ to 19 results in:
݂ሺ19ሻ ൌ 1ଶ ൅ 9ଶ ൌ 82
݂ሺ82ሻ ൌ 8ଶ ൅ 2ଶ ൌ 68
݂ሺ68ሻ ൌ 6ଶ ൅ 8ଶ ൌ 100
݂ሺ100ሻ ൌ 1ଶ ൅ 0ଶ ൅ 0ଶ ൌ 1
However, not all natural numbers are happy. You could try 5 and you will see that 5 is not a happy number. If is not a happy number, it has been proved by mathematicians that repeatedly applying function ݂ to ݊ reaches the following cycle:
4 → 16 → 37 → 58 → 89 → 145 → 42 → 20 → 4.
Write a program that decides if a given natural number ݊ is a happy number or not.

Input

Your program is to read from standard input. The input consists of a single line that contains an integer, ݊
(1 ൑ ݊ ൑ 1,000,000,000)

Output

Your program is to write to standard output. Print exactly one line. If the given number ݊ is a happy number,print out HAPPY; otherwise, print out UNHAPPY.
The following shows sample input and output for two test cases.

Sample Input 1

19

Output for the Sample Input 1

HAPPY

Sample Input 2

5

Output for the Sample Input 2

UNHAPPY

题解

题意

按照题中操作，如果能得到1，就是happy。反之，输出unhappy

思路

简单的思路，按顺序模拟即可。

代码

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <map>

using namespace std;

int n;
map <int, int> m;

int main()
{
	bool flag = true;
	scanf("%d", &n);
	m.clear();
	while (n != 1)
	{
		if (m[n])
		{
			flag = false;
			break;
		}
		m[n] = 1;
		int temp = 0;
		while (n)
		{
			temp += (n%10)*(n%10);
			n /= 10;
		}
		n = temp;
	}
	if (flag)
		printf("HAPPY\n");
	else
		printf("UNHAPPY\n");
	return 0;
}