> For the complete documentation index, see [llms.txt](https://hao-fu-1.gitbook.io/oj/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hao-fu-1.gitbook.io/oj/math.md).

# Math

- [Geometry](https://hao-fu-1.gitbook.io/oj/math/geometry-1.md)
- [Largest Triangle Area](https://hao-fu-1.gitbook.io/oj/math/geometry-1/largest-triangle-area.md): https://leetcode.com/problems/largest-triangle-area/
- [593. Valid Square](https://hao-fu-1.gitbook.io/oj/math/geometry-1/593.-valid-square.md): https://leetcode.com/problems/valid-square/
- [Count Primes](https://hao-fu-1.gitbook.io/oj/math/count-primes.md): https://leetcode.com/problems/count-primes/description/
- [441. Arranging Coins](https://hao-fu-1.gitbook.io/oj/math/arranging-coins.md): https://leetcode.com/problems/arranging-coins/description/
- [Permutation Sequence](https://hao-fu-1.gitbook.io/oj/math/permutation-sequence.md)
- [Range Addition II](https://hao-fu-1.gitbook.io/oj/math/range-addition-ii.md)
- [进制转换](https://hao-fu-1.gitbook.io/oj/math/jin-zhi-zhuan-huan.md)
- [Excel Sheet Column Title](https://hao-fu-1.gitbook.io/oj/math/jin-zhi-zhuan-huan/excel-sheet-column-title.md)
- [Excel Sheet Column Number](https://hao-fu-1.gitbook.io/oj/math/jin-zhi-zhuan-huan/excel-sheet-column-number.md)
- [405. Convert a Number to Hexadecimal](https://hao-fu-1.gitbook.io/oj/math/jin-zhi-zhuan-huan/405.-convert-a-number-to-hexadecimal.md): https://leetcode.com/problems/convert-a-number-to-hexadecimal/
- [660 Remove 9](https://hao-fu-1.gitbook.io/oj/math/jin-zhi-zhuan-huan/660-remove-9.md)
- [Maximum Product of Three Numbers](https://hao-fu-1.gitbook.io/oj/math/maximum-product-of-three-numbers.md)
- [Power of Three](https://hao-fu-1.gitbook.io/oj/math/power-of-three.md)
- [Ugly Number](https://hao-fu-1.gitbook.io/oj/math/ugly-number.md)
- [1344. Angle Between Hands of a Clock](https://hao-fu-1.gitbook.io/oj/math/1344.-angle-between-hands-of-a-clock.md): https://leetcode.com/problems/angle-between-hands-of-a-clock/
- [66. Plus One](https://hao-fu-1.gitbook.io/oj/math/plus-one.md): https://leetcode.com/problems/plus-one/description/
- [780. Reaching Points](https://hao-fu-1.gitbook.io/oj/math/780.-reaching-points.md): https://leetcode.com/problems/reaching-points/
- [564. Find the Closest Palindrome](https://hao-fu-1.gitbook.io/oj/math/564.-find-the-closest-palindrome.md): https://leetcode.com/problems/find-the-closest-palindrome/description/
- [Sqrt(x)](https://hao-fu-1.gitbook.io/oj/math/sqrtx.md)
- [Valid Perfect Square](https://hao-fu-1.gitbook.io/oj/math/sqrtx/valid-perfect-square.md)
- [1390. Four Divisors](https://hao-fu-1.gitbook.io/oj/math/sqrtx/1390.-four-divisors.md): https://leetcode.com/problems/four-divisors/
- [Factorial Trailing Zeroes](https://hao-fu-1.gitbook.io/oj/math/factorial-trailing-zeroes.md)
- [Strobogrammatic Number](https://hao-fu-1.gitbook.io/oj/math/strobogrammatic-number.md): https://leetcode.com/problems/strobogrammatic-number/description/
- [296. Best Meeting Point](https://hao-fu-1.gitbook.io/oj/math/296.-best-meeting-point.md)
- [排列组合](https://hao-fu-1.gitbook.io/oj/math/pai-lie-zu-he.md)
- [1643. Kth Smallest Instructions](https://hao-fu-1.gitbook.io/oj/math/pai-lie-zu-he/1643.-kth-smallest-instructions.md): https://leetcode.com/problems/kth-smallest-instructions/
- [Perfect Number](https://hao-fu-1.gitbook.io/oj/math/perfect-number.md)
- [加法](https://hao-fu-1.gitbook.io/oj/math/jia-fa.md)
- [67. Add Binary](https://hao-fu-1.gitbook.io/oj/math/jia-fa/add-binary.md): https://leetcode.com/problems/add-binary/description/
- [Add Strings](https://hao-fu-1.gitbook.io/oj/math/jia-fa/add-strings.md)
- [Multiply Strings](https://hao-fu-1.gitbook.io/oj/math/jia-fa/multiply-strings.md): https://leetcode.com/problems/multiply-strings/description/
- [Nth Digit](https://hao-fu-1.gitbook.io/oj/math/nth-digit.md)
- [Roman to Integer](https://hao-fu-1.gitbook.io/oj/math/roman-to-integer.md)
- [Integer to Roman](https://hao-fu-1.gitbook.io/oj/math/roman-to-integer/integer-to-roman.md)
- [Integer to English Words](https://hao-fu-1.gitbook.io/oj/math/roman-to-integer/integer-to-english-words.md): https://leetcode.com/problems/integer-to-english-words/description/
- [Pow(x, n)](https://hao-fu-1.gitbook.io/oj/math/powx-n.md): https://leetcode.com/problems/powx-n/description/
- [Divide Two Integers](https://hao-fu-1.gitbook.io/oj/math/divide-two-integers.md): https://leetcode.com/problems/divide-two-integers/description/
- [GCD](https://hao-fu-1.gitbook.io/oj/math/gcd.md)
- [Geometry](https://hao-fu-1.gitbook.io/oj/math/geometry.md)
- [Max Points on a Line](https://hao-fu-1.gitbook.io/oj/math/geometry/max-points-on-a-line.md): https://leetcode.com/problems/max-points-on-a-line/description/
- [Rectangle Area](https://hao-fu-1.gitbook.io/oj/math/geometry/rectangle-area.md)
- [Line Reflection](https://hao-fu-1.gitbook.io/oj/math/geometry/line-reflection.md)
- [Super Pow](https://hao-fu-1.gitbook.io/oj/math/super-pow.md)
- [829. Consecutive Numbers Sum](https://hao-fu-1.gitbook.io/oj/math/829.-consecutive-numbers-sum.md): https://leetcode.com/problems/consecutive-numbers-sum/
- [找规律](https://hao-fu-1.gitbook.io/oj/math/zhao-gui-lv.md)
- [Rotate Function](https://hao-fu-1.gitbook.io/oj/math/zhao-gui-lv/rotate-function.md)
- [Bulb Switcher](https://hao-fu-1.gitbook.io/oj/math/zhao-gui-lv/bulb-switcher.md): https://leetcode.com/problems/bulb-switcher/description/
- [Add Digits](https://hao-fu-1.gitbook.io/oj/math/zhao-gui-lv/add-digits.md)
- [1247. Minimum Swaps to Make Strings Equal](https://hao-fu-1.gitbook.io/oj/math/zhao-gui-lv/1247.-minimum-swaps-to-make-strings-equal.md): https://leetcode.com/contest/weekly-contest-161/problems/minimum-swaps-to-make-strings-equal/
- [Bulb Switcher II](https://hao-fu-1.gitbook.io/oj/math/zhao-gui-lv/bulb-switcher-ii.md)
- [1503. Last Moment Before All Ants Fall Out of a Plank](https://hao-fu-1.gitbook.io/oj/math/zhao-gui-lv/1503.-last-moment-before-all-ants-fall-out-of-a-plank.md)
- [Next Closest Time](https://hao-fu-1.gitbook.io/oj/math/next-closest-time.md)
- [1362. Closest Divisors](https://hao-fu-1.gitbook.io/oj/math/1362.-closest-divisors.md): https://leetcode.com/problems/closest-divisors/
- [Missing Ranges](https://hao-fu-1.gitbook.io/oj/math/missing-ranges.md)
- [Strobogrammatic Number III](https://hao-fu-1.gitbook.io/oj/math/strobogrammatic-number-iii.md)
- [1154. Day of the Year](https://hao-fu-1.gitbook.io/oj/math/1154.-day-of-the-year.md): https://leetcode.com/problems/day-of-the-year/
- [1360. Number of Days Between Two Dates](https://hao-fu-1.gitbook.io/oj/math/1360.-number-of-days-between-two-dates.md): https://leetcode.com/problems/number-of-days-between-two-dates/
- [Majority Element](https://hao-fu-1.gitbook.io/oj/math/majority-element.md)
- [Majority Element II](https://hao-fu-1.gitbook.io/oj/math/majority-element/majority-element-ii.md)
- [311. Sparse Matrix Multiplication](https://hao-fu-1.gitbook.io/oj/math/sparse-matrix-multiplication.md): https://leetcode.com/problems/sparse-matrix-multiplication/description/
- [Maximum Swap](https://hao-fu-1.gitbook.io/oj/math/maximum-swap.md)
- [Reservoir Sampling](https://hao-fu-1.gitbook.io/oj/math/reservoir-sampling.md)
- [Random Pick Index](https://hao-fu-1.gitbook.io/oj/math/reservoir-sampling/random-pick-index.md): https://leetcode.com/problems/random-pick-index/description/
- [382. Linked List Random Node](https://hao-fu-1.gitbook.io/oj/math/reservoir-sampling/linked-list-random-node.md): https://leetcode.com/problems/linked-list-random-node/description/
- [Integer Break](https://hao-fu-1.gitbook.io/oj/math/integer-break.md)
- [Largest Perimeter Triangle](https://hao-fu-1.gitbook.io/oj/math/largest-perimeter-triangle.md)
- [1363. Largest Multiple of Three](https://hao-fu-1.gitbook.io/oj/math/1363.-largest-multiple-of-three.md): https://leetcode.com/problems/largest-multiple-of-three/
- [Binary Prefix Divisible By 5](https://hao-fu-1.gitbook.io/oj/math/binary-prefix-divisible-by-5.md)
- [随机数](https://hao-fu-1.gitbook.io/oj/math/sui-ji-shu.md)
- [470. Implement Rand10() Using Rand7()](https://hao-fu-1.gitbook.io/oj/math/sui-ji-shu/470.-implement-rand10-using-rand7.md): https://leetcode.com/problems/implement-rand10-using-rand7/description/
- [478. Generate Random Point in a Circle](https://hao-fu-1.gitbook.io/oj/math/sui-ji-shu/478.-generate-random-point-in-a-circle.md): https://leetcode.com/problems/generate-random-point-in-a-circle/description/
- [528. Random Pick with Weight](https://hao-fu-1.gitbook.io/oj/math/sui-ji-shu/528.-random-pick-with-weight.md): https://leetcode.com/problems/random-pick-with-weight/description/
- [710. Random Pick with Blacklist](https://hao-fu-1.gitbook.io/oj/math/sui-ji-shu/710.-random-pick-with-blacklist.md): https://leetcode.com/problems/random-pick-with-blacklist/description/
- [381. Insert/Del GetRandom O(1)-Duplicates allowed](https://hao-fu-1.gitbook.io/oj/math/sui-ji-shu/381.-insert-del-getrandom-o-1-duplicates-allowed.md)