[C 語言] 符號常數(Symbolic Constants)
撰寫符號常數(Symbolic Constants)是種提高『原始碼可讀性』的方法。正如經典的攝氏溫度與華氏溫度的轉換,其中邊界值與更新值等的 lower、upper、step 其實都是有意義的數字,尤其是溫度的邊界值。
Read More »[C 語言] 符號常數(Symbolic Constants)撰寫符號常數(Symbolic Constants)是種提高『原始碼可讀性』的方法。正如經典的攝氏溫度與華氏溫度的轉換,其中邊界值與更新值等的 lower、upper、step 其實都是有意義的數字,尤其是溫度的邊界值。
Read More »[C 語言] 符號常數(Symbolic Constants)在前一篇筆記當中,紀錄了如何攝氏溫度與華氏溫度之間如何透過程式轉換([C 語言] 變數(Variables)與算術表達式(Arithmetic Expressions))。在過程中,我們透過 while
迴圈不斷增加華氏溫度,並查看轉換出的攝氏溫度結果。
而在程式當中,若希望程式能反覆執行同樣的指令,則也可以使用 for
迴圈(for-loop)來做到這件事。
電腦(Computer)在中國也被稱為『計算機』,能夠輔助人類『計算』自然是它開發出來最重要的功能之一。
本小節透過攝氏溫度(°C)與華氏溫度(°F)的轉換,闡述何者為『變數』、何者又是算術表達式。
Read More »[C 語言] 變數(Variables)與算術表達式(Arithmetic Expressions)C 語言是最常見的程式語言之一,能夠在許多 Unix 系統中瞧見它的身影,許多系統與程式也都是使用 C 語言來進行開發。
所以 C 語言可說是程式開發人員熟悉起來絕對沒有壞處的程式語言。
Read More »[C 語言] 使用 gcc 指令編譯,並印出 Hello WorldThe count-and-say sequence is a sequence of digit strings defined by the recursive formula:
- countAndSay(1) = "1"
- countAndSay(n) is the way you would "say" the digit string from countAndSay(n-1), which is then converted into a different digit string.
To determine how you "say" a digit string, split it into the minimal number of groups so that each group is a contiguous section all of the same character. Then for each group, say the number of characters, then say the character. To convert the saying into a digit string, replace the counts with a number and concatenate every saying.
Given a positive integer n, return the nth term of the count-and-say sequence.
Example:
Input: n = 1
Output: "1"
Explanation: This is the base case.
Input: n = 4
Output: "1211"
Explanation:
countAndSay(1) = "1"
countAndSay(2) = say "1" = one 1 = "11"
countAndSay(3) = say "11" = two 1's = "21"
countAndSay(4) = say "21" = one 2 + one 1 = "12" + "11" = "1211"
Read More »LeetCode: 38-Count and Say 解題紀錄Given a sorted array nums, remove the duplicates in-place such that each element appears only once and returns the new length.
Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.
Clarification:
Confused why the returned value is an integer but your answer is an array?
Note that the input array is passed in by reference, which means a modification to the input array will be known to the caller as well.
Example:
Input: nums = [1,1,2]
Output: 2, nums = [1,2]
Explanation: Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively. It doesn't matter what you leave beyond the returned length.
題目輸入一個由小到大排序的陣列,我們需要回傳『沒有重複元素陣列長度』,並將這些沒有重複的元素移動至該陣列的開頭。
當然你可以選擇刪除掉重複的元素,但驗證時只會依照你回傳的長度進行該陣列的檢測。比方說你回傳 1,那麼驗證機制只會檢測陣列開頭第 1 個元素。
Read More »LeetCode: 26-Remove Duplicates from Sorted Array 解題紀錄Given the head of a linked list, remove the nth node from the end of the list and return its head.
Follow up: Could you do this in one pass?
Example:
Input: head = [1,2,3,4,5], n = 2
Output: [1,2,3,5]
本題給定一個鏈結串列(Linked List),而我們要做的,便是將倒數第 n 個元素刪除,並回傳刪除後的 Linked List。
Read More »LeetCode: 19-Remove Nth Node From End of List 解題紀錄Given an array nums of n integers and an integer target, are there elements a, b, c, and d in nums such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target.
Notice that the solution set must not contain duplicate quadruplets.
Example:
Input: nums = [1,0,-1,0,-2,2], target = 0
Output: [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]
這個題目是 2Sum、3Sum 的衍伸版,同樣給定一個整數陣列輸入,我們要找出由四個數加總為 0 的所有組合。
Read More »LeetCode: 18-4Sum 解題紀錄Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring.
Example:
Input: s = "(()"
Output: 2
Explanation: The longest valid parentheses substring is "()".
Input: s = ")()())"
Output: 4
Explanation: The longest valid parentheses substring is "()()".
這個題目輸入一個只由 '(' 或是 ')' 組成的字串,而我們要做的,就是判斷最長的『合理』子字串長度。
比方說, "()" 就是合理的子字串、")(" 就是個不合理的子字串。
Read More »LeetCode: 32-Longest Valid Parentheses 解題紀錄Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution.
Example:
Input: nums = [-1,2,1,-4], target = 1
Output: 2
Explanation: The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
Constraints:
3 <= nums.length <= 10^3
-10^3 <= nums[i] <= 10^3
-10^4 <= target <= 10^4
這個題目跟 15 題非常相似,同樣是給定一組整數陣列輸入,不過還多給了一個目標值 target。我們需要找出 3 個數值,使其加總值越接近 target 越好。
需要注意的是,我們要返回的並不是找到的陣列,而是直接返回最接近 target 的數值。
Read More »LeetCode: 16-3Sum Closest 解題紀錄