60 lines
968 B
JavaScript
60 lines
968 B
JavaScript
/*
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* @lc app=leetcode id=326 lang=javascript
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*
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* [326] Power of Three
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*
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* https://leetcode.com/problems/power-of-three/description/
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*
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* algorithms
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* Easy (41.43%)
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* Total Accepted: 178.8K
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* Total Submissions: 430.4K
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* Testcase Example: '27'
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*
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* Given an integer, write a function to determine if it is a power of three.
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*
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* Example 1:
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*
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*
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* Input: 27
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* Output: true
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*
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*
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* Example 2:
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*
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*
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* Input: 0
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* Output: false
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*
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* Example 3:
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*
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*
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* Input: 9
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* Output: true
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*
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* Example 4:
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*
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*
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* Input: 45
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* Output: false
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*
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* Follow up:
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* Could you do it without using any loop / recursion?
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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 isPowerOfThree = function(n) {
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// tag: 数论
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// let i = 0;
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// while(Math.pow(3, i) < n) {
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// i++;
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// }
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// return Math.pow(3, i) === n;
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// 巧用整除
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return n > 0 && Math.pow(3, 19) % n === 0;
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};
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// 扩展： 这个方法可以扩展到任意质数，合数则不行
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