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LeetCode - Problems - Algorithms - 35. Search Insert Position Problem Description Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. My Solution (C#) nums에 target을 insert한다고 가정 했을 때, insert 되는 위치를 return하는 문제. nums는 오름차순으로 정렬되어있고, target 또한 오름차순에 맞게 insert 되어야 한다는 조건이 있다. ..

LeetCode - Problems - Algorithms - 28. Implement strStr() Problem Description My Solution (C#) 변수 이름에서 알 수 있듯이, 주어진 string 건초더미에서 string 바늘이 있는지 찾는 문제이다. C#의 IndexOf (C의 경우는 StrStr)를 구현하는 문제다. Description을 끝까지 안읽어서 (끝까지 읽읍시다...) IndexOf를 사용해서 풀었다. (??) // Implementing IndexOf by using IndexOf (???) public class Solution { public int StrStr(string haystack, string needle) { if (string.IsNullOrEmp..

LeetCode - Problems - Algorithms - 27. Remove Element Problem Description My Solution (C#) public class Solution { public int RemoveElement(int[] nums, int val) { if (nums.Length == 0) return 0; int index = 0; foreach (int num in nums) { if (num != val) { nums[index] = num; index++; } } return index; } } 26. Remove Duplicates from Sorted Array와 비슷하게 풀었다. [LeetCode] 26. Remove Duplicates from Sor..

LeetCode - Problems - Algorithms - 26. Remove Duplicates from Sorted Array Problem Description My Solution (C#) public class Solution { public int RemoveDuplicates(int[] nums) { if (nums.Length == 0) return 0; int index = 0; for (int i = 1; i < nums.Length; i++) { if (nums[index] != nums[i]) { nums[++index] = nums[i]; } } return ++index; } } C#의 regular array는 길이를 조절할 수 없는 array이다. 그러다 문제는 array..

LeetCode - Problems - Algorithms - 21. Merge Two Sorted Lists Problem Description 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. My Solution (C#) /** * Definition for singly-linked list. * public class ListNode { * public int val; * public ListNode next; * public ListNode(int val=0, ListNode next=null) ..

LeetCode - Problems - Algorithms - 20. Valid Parentheses Problem Description Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Example 1: Input: s = "()" Output: true Example 2: Input: s =..

LeetCode - Problems - Algorithms - 14. Longest Common Prefix Problem Description 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 1: Input: strs = ["flower","flow","flight"] Output: "fl" Example 2: Input: strs = ["dog","racecar","car"] Output: "" Explanation: There is no common prefix among the..

LeetCode - Problems - Algorithms - 13. Roman to Integer Problem Description 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. Roma..

LeetCode - Problems - Algorithms - 9. Palindrome Number Problem Description Given an integer x, return true if x is palindrome integer. An integer is a palindrome when it reads the same backward as forward. For example, 121 is palindrome while 123 is not. Example 1: Input: x = 121 Output: true Example 2: Input: x = -121 Output: false Explanation: From left to right, it reads -121. From right to ..

LeetCode - Problems - Algorithms - 7.Reverse Integer Problem Description Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-2^31, 2^31 - 1], then return 0. Assume the environment does not allow you to store 64-bit integers (signed or unsigned). Example 1: Input: x = 123 Output: 321 Example 2: Input: ..