[Leetcode 202, Easy] Happy Number
2015-05-04 10:34
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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
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.
Analysis:
Solutions:
C++:
Python:
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.
Analysis:
Solutions:
C++:
bool isHappy(int n) { if(n == 0) return false; if(n == 1) return true; int max_loops = 100; int num = n; for(int i = 0; i < max_loops; ++i) { vector<int> digits; while(num != 0) { int digit = num % 10; digits.push_back(digit); num /= 10; } for(int i = 0; i < digits.size(); ++i) num += digits[i] * digits[i]; if(num == 1) return true; } return false; }Java:
Python:
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