61 lines
1.3 KiB
JavaScript
61 lines
1.3 KiB
JavaScript
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/*
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* @lc app=leetcode id=202 lang=javascript
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*
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* [202] Happy Number
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*
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* https://leetcode.com/problems/happy-number/description/
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*
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* algorithms
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* Easy (44.36%)
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* Total Accepted: 227.2K
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* Total Submissions: 505.7K
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* Testcase Example: '19'
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*
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* Write an algorithm to determine if a number is "happy".
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*
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* A happy number is a number defined by the following process: Starting with
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* any positive integer, replace the number by the sum of the squares of its
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* digits, and repeat the process until the number equals 1 (where it will
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* stay), or it loops endlessly in a cycle which does not include 1. Those
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* numbers for which this process ends in 1 are happy numbers.
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*
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* Example:
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*
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*
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* Input: 19
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* Output: true
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* Explanation:
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* 1^2 + 9^2 = 82
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* 8^2 + 2^2 = 68
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* 6^2 + 8^2 = 100
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* 1^2 + 0^2 + 0^2 = 1
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*
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*/
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function squareSum(n) {
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let sum = 0, tmp;
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while (n) {
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tmp = n % 10;
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sum += tmp * tmp;
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n = Math.floor(n / 10);
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}
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return sum;
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}
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function isHappyWithMapper(n, visited) {
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if (n === 1) return true;
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if (visited[n]) return false;
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visited[n] = true;
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return isHappyWithMapper(squareSum(n), visited);
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}
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/**
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* @param {number} n
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* @return {boolean}
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*/
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var isHappy = function(n) {
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const visited = {};
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return isHappyWithMapper(n, visited);
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};
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