Happy Number Problem
Description
LeetCode Problem 202.
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:
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Input: n = 19
Output: true
Explanation:
1^2 + 9^2 = 82
8^2 + 2^2 = 68
6^2 + 8^2 = 100
1^2 + 0^2 + 0^2 = 1
Example 2:
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Input: n = 2
Output: false
Constraints:
- 1 <= n <= 2^31 - 1
Sample C++ Code
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class Solution {
public:
bool isHappy(int n) {
map<int, int> ht;
int m;
bool happy = false;
while (1) {
ht[n] = 1;
m = 0;
while (n > 0) {
m += (n % 10) * (n % 10);
n /= 10;
}
n = m;
if (n == 1) {
happy = true;
break;
}
if (ht.find(n) != ht.end()) {
happy = false;
break;
}
}
return happy;
}
};