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notes/Leetcode 题解 - 数学.md
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@ -46,7 +46,9 @@ x 和 y 的最小公倍数为：lcm(x,y) = 2<sup>max(m0,n0)</sup> \* 3<sup>max(
## 1. 生成素数序列
[204. Count Primes (Easy)](https://leetcode.com/problems/count-primes/description/)
204\. Count Primes (Easy)
[Leetcode](https://leetcode.com/problems/count-primes/description/) / [力扣](https://leetcode-cn.com/problems/count-primes/description/)
埃拉托斯特尼筛法在每次找到一个素数时，将能被素数整除的数排除掉。
@ -122,7 +124,9 @@ public int gcd(int a, int b) {
## 1. 7 进制
[504. Base 7 (Easy)](https://leetcode.com/problems/base-7/description/)
504\. Base 7 (Easy)
[Leetcode](https://leetcode.com/problems/base-7/description/) / [力扣](https://leetcode-cn.com/problems/base-7/description/)
```java
public String convertToBase7(int num) {
@ -153,7 +157,9 @@ public String convertToBase7(int num) {
## 2. 16 进制
[405. Convert a Number to Hexadecimal (Easy)](https://leetcode.com/problems/convert-a-number-to-hexadecimal/description/)
405\. Convert a Number to Hexadecimal (Easy)
[Leetcode](https://leetcode.com/problems/convert-a-number-to-hexadecimal/description/) / [力扣](https://leetcode-cn.com/problems/convert-a-number-to-hexadecimal/description/)
```html
Input:
@ -186,7 +192,9 @@ public String toHex(int num) {
## 3. 26 进制
[168. Excel Sheet Column Title (Easy)](https://leetcode.com/problems/excel-sheet-column-title/description/)
168\. Excel Sheet Column Title (Easy)
[Leetcode](https://leetcode.com/problems/excel-sheet-column-title/description/) / [力扣](https://leetcode-cn.com/problems/excel-sheet-column-title/description/)
```html
1 -> A
@ -214,7 +222,9 @@ public String convertToTitle(int n) {
## 1. 统计阶乘尾部有多少个 0
[172. Factorial Trailing Zeroes (Easy)](https://leetcode.com/problems/factorial-trailing-zeroes/description/)
172\. Factorial Trailing Zeroes (Easy)
[Leetcode](https://leetcode.com/problems/factorial-trailing-zeroes/description/) / [力扣](https://leetcode-cn.com/problems/factorial-trailing-zeroes/description/)
尾部的 0 由 2 * 5 得来，2 的数量明显多于 5 的数量，因此只要统计有多少个 5 即可。
@ -232,7 +242,9 @@ public int trailingZeroes(int n) {
## 1. 二进制加法
[67. Add Binary (Easy)](https://leetcode.com/problems/add-binary/description/)
67\. Add Binary (Easy)
[Leetcode](https://leetcode.com/problems/add-binary/description/) / [力扣](https://leetcode-cn.com/problems/add-binary/description/)
```html
a = "11"
@ -260,7 +272,9 @@ public String addBinary(String a, String b) {
## 2. 字符串加法
[415. Add Strings (Easy)](https://leetcode.com/problems/add-strings/description/)
415\. Add Strings (Easy)
[Leetcode](https://leetcode.com/problems/add-strings/description/) / [力扣](https://leetcode-cn.com/problems/add-strings/description/)
字符串的值为非负整数。
@ -282,7 +296,9 @@ public String addStrings(String num1, String num2) {
## 1. 改变数组元素使所有的数组元素都相等
[462. Minimum Moves to Equal Array Elements II (Medium)](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii/description/)
462\. Minimum Moves to Equal Array Elements II (Medium)
[Leetcode](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii/description/) / [力扣](https://leetcode-cn.com/problems/minimum-moves-to-equal-array-elements-ii/description/)
```html
Input:
@ -378,7 +394,9 @@ private void swap(int[] nums, int i, int j) {
## 1. 数组中出现次数多于 n / 2 的元素
[169. Majority Element (Easy)](https://leetcode.com/problems/majority-element/description/)
169\. Majority Element (Easy)
[Leetcode](https://leetcode.com/problems/majority-element/description/) / [力扣](https://leetcode-cn.com/problems/majority-element/description/)
先对数组排序，最中间那个数出现次数一定多于 n / 2。
@ -406,7 +424,9 @@ public int majorityElement(int[] nums) {
## 1. 平方数
[367. Valid Perfect Square (Easy)](https://leetcode.com/problems/valid-perfect-square/description/)
367\. Valid Perfect Square (Easy)
[Leetcode](https://leetcode.com/problems/valid-perfect-square/description/) / [力扣](https://leetcode-cn.com/problems/valid-perfect-square/description/)
```html
Input: 16
@ -432,7 +452,9 @@ public boolean isPerfectSquare(int num) {
## 2. 3 的 n 次方
[326. Power of Three (Easy)](https://leetcode.com/problems/power-of-three/description/)
326\. Power of Three (Easy)
[Leetcode](https://leetcode.com/problems/power-of-three/description/) / [力扣](https://leetcode-cn.com/problems/power-of-three/description/)
```java
public boolean isPowerOfThree(int n) {
@ -442,7 +464,9 @@ public boolean isPowerOfThree(int n) {
## 3. 乘积数组
[238. Product of Array Except Self (Medium)](https://leetcode.com/problems/product-of-array-except-self/description/)
238\. Product of Array Except Self (Medium)
[Leetcode](https://leetcode.com/problems/product-of-array-except-self/description/) / [力扣](https://leetcode-cn.com/problems/product-of-array-except-self/description/)
```html
For example, given [1,2,3,4], return [24,12,8,6].
@ -473,7 +497,9 @@ public int[] productExceptSelf(int[] nums) {
## 4. 找出数组中的乘积最大的三个数
[628. Maximum Product of Three Numbers (Easy)](https://leetcode.com/problems/maximum-product-of-three-numbers/description/)
628\. Maximum Product of Three Numbers (Easy)
[Leetcode](https://leetcode.com/problems/maximum-product-of-three-numbers/description/) / [力扣](https://leetcode-cn.com/problems/maximum-product-of-three-numbers/description/)
```html
Input: [1,2,3,4]