最近看到新聞，發現現在在 Unix-liked 系統中大家常用的 sudo 工具，原來存在著一個『堆積緩衝溢位漏洞』的 BUG（編號 CVE-2021-3156）。
目前在以下版本確認了能夠取得完整的 root 權限：
而據報導、以及我粗略看過的幾個討論區，幾乎都在建議大家迅速升級該套件版本。這個 BUG 在 2021/01 月中發現而通報 sudo 開發單位，差不多一個禮拜多，新版的修復就已經上線了。
以下我簡單紀錄該如何升級 sudo 版本。
Read More »[Linux] 升級 sudo 套件的幾個方法 
Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.
If such an arrangement is not possible, it must rearrange it as the lowest possible order (i.e., sorted in ascending order).
The replacement must be in place and use only constant extra memory.Example:
Input: nums = [1,2,3]
Output: [1,3,2]
Input: nums = [3,2,1]
Output: [1,2,3]
Input: nums = [1,1,5]
Output: [1,5,1]
Input: nums = [1]
Output: [1]題目給定輸入一個陣列，我們要將陣列排列成『下一個較大的值』。比方說題目輸入了 [1,2,3]，那麼我們就不能排列成 [3,1,2]、而是要排列成 [1,3,2] —— 因為 132 才下一個較大的值，而非 312。
而當題目給定的陣列沒有下一個較大的排列時，則將陣列『從小排到大』。
順帶一提這題不會返回任何值，直接處理輸入陣列即可。
Read More »LeetCode: 31-Next Permutation 解題紀錄 Merge two sorted linked lists and return it as a sorted list. The list should be made by splicing together the nodes of the first two lists.
Example:
Input: l1 = [1,2,4], l2 = [1,3,4]
Output: [1,1,2,3,4,4]題目輸入兩個已經排序過的 Linked List，而我們要將其『合併』，並回傳同樣排序過的 Linked List。
Read More »LeetCode: 21-Merge Two Sorted Lists 解題紀錄 su 是一個在 Linux 系統中相當常見的指令，經常用於『切換使用者』。一開始我以為 su 是 switch user 的縮寫，但查詢之下，這才發現其實應該是 substitute user （替代使用者）的縮寫（完全不重要）。
Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.Symbol Value
I 1
V 5
X 10
L 50
C 100
D 500
M 1000For example, 2 is written as II in Roman numeral, just two one's added together. 12 is written as XII, which is simply X + II. The number 27 is written as XXVII, which is XX + V + II.
Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII. Instead, the number four is written as IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used:I can be placed before V (5) and X (10) to make 4 and 9. X can be placed before L (50) and C (100) to make 40 and 90. C can be placed before D (500) and M (1000) to make 400 and 900.Given a roman numeral, convert it to an integer.Example:
Input: s = "LVIII"
Output: 58
Explanation: L = 50, V= 5, III = 3.
Input: s = "MCMXCIV"
Output: 1994
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.Given n non-negative integers a1, a2, ..., an , where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of the line i is at (i, ai) and (i, 0). Find two lines, which, together with the x-axis forms a container, such that the container contains the most water.
Notice that you may not slant the container.Example:
Input: height = [1,8,6,2,5,4,8,3,7]
Output: 49
Explanation: The above vertical lines are represented by array [1,8,6,2,5,4,8,3,7]. In this case, the max area of water (blue section) the container can contain is 49.這個題目也是相當地經典，就是題目給定一陣列，陣列內為由左到右每個 ...... ㄜ，這裡就叫『木板』好了，每個木板的高度。
而不同的木板之間，距離單位都是 1。我們要做的就是，找出能讓容器積蓄最多的水兩片木板，最後，回傳可以積蓄水的最大值。
Read More »LeetCode: 11-Container With Most Water 解題紀錄 Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.
Symbol Value
I 1
V 5
X 10
L 50
C 100
D 500
M 1000
For example, 2 is written as II in Roman numeral, just two one's added together. 12 is written as XII, which is simply X + II. The number 27 is written as XXVII, which is XX + V + II.
Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII. Instead, the number four is written as IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used:
- I can be placed before V (5) and X (10) to make 4 and 9.
- X can be placed before L (50) and C (100) to make 40 and 90.
- C can be placed before D (500) and M (1000) to make 400 and 900.
Given an integer, convert it to a roman numeral.Example:
Input: num = 3
Output: "III"
Input: num = 58
Output: "LVIII"
Input: num = 1994
Output: "MCMXCIV"題目給定一整數值，而我們要做的便是將整數值轉換成羅馬數字 —— 也就是說，我們需要回傳字串型態的答案。
Read More »LeetCode: 12-Integer to Roman 解題紀錄 Write a function to find the longest common prefix string amongst an array of strings.
If there is no common prefix, return an empty string "".Example:
Input: strs = ["flower","flow","flight"]
Output: "fl"
Input: strs = ["dog","racecar","car"]
Output: ""題目給定一陣列，裡頭存放許多組字串，而我們要做的就是找到他們共同的前綴字串並回傳；若無共同的前綴，則回傳空字串 ""。
Read More »LeetCode: 14-Longest Common Prefix 解題紀錄