LeetCode263_263. Ugly numbers
1. Description
An ugly number is a positive integer that contains only prime factors 2, 3, and 5.
Given an integer n, please judge whether n is an ugly number. If yes, return true; otherwise, return false.
Example 1:
输入：n = 6
输出：true
解释：6 = 2 × 3
Example 2:
输入：n = 1
输出：true
解释：1 没有质因数，因此它的全部质因数是 {2, 3, 5} 的空集。习惯上将其视作第一个丑数。
Example 3:
输入：n = 14
输出：false
解释：14 不是丑数，因为它包含了另外一个质因数 7 。
hint:
-2 to the 31st power <= n <= 2 to the 31st power - 1
Two, solution
Method 1: Just keep dividing by 2 3 5 until the result is 1
//AC Your runtime beats 61.46 % of java submissions.
// 1012 / 1012 test cases passed. Status: Accepted Runtime: 4 ms
//思路就是就是一直除以 2 3 5 直到结果是1即可
public boolean isUgly(int num) {
boolean res = false;
if (num <= 0) {
return false;
} else if (num == 1) {
//这个判断也可以不单独写。因为1本身题目就定义为Ugly Number
res = true;
} else {
while (num % 2 == 0)
num /= 2;
while (num % 3 == 0)
num /= 3;
while (num % 5 == 0)
num /= 5;
if (num == 1)
res = true;
}
return res;
}
LeetCode 217. Existence of Duplicate Elements
LeetCode 229. Majority II
LeetCode 231. Powers of 2
LeetCode 234. Palindrome Linked
List LeetCode 237. Delete Nodes in a Linked List
LeetCode 242. Valid Alphabetic Words
LeetCode 257. All Paths in a Binary Tree
LeetCode 258 . Add everyone
LeetCode 263. Ugly numbers
LeetCode 268. Missing numbers
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