꿈꾸는공학도

사실 Palindrome 문제는 유형도 많고, DP를 이용해서 풀면 편하지만 너~무 짜친다. 아오 하기 싫어! Longest Palindrome Substring(이하 LPS) 문제를 2개 풀게 됐는데, 하나는 10초컷 / 하나는 30분을 고민해도 어렵다.. 쉬운 문제는 아래와 같다.def is_palindromic(s: str) -> bool: """ > input 's' - A string consisting of only lowercase English letters (1 return a boolean """ # WRITE YOUR CODE HERE n = len(s) left = 0 right = n-1 while left  그냥 input에 대해..

https://leetcode.com/problems/unique-binary-search-trees/description/Given an integer n, return the number of structurally unique BST's (binary search trees) which has exactly n nodes of unique values from 1 to n. Example 1:Input: n = 3Output: 5Example 2:Input: n = 1Output: 1 Constraints:1 그래도 가볍게나마 BST문제도 풀어봐야지..! Linked List , Tree 이런 걸 자꾸만 건들자 근데 이건,, Tree 문제라기보단 수학 문제 같다.. 흐음..  1. Python 일단..

https://leetcode.com/problems/minimum-number-of-operations-to-move-all-balls-to-each-box/description/?envType=daily-question&envId=2025-01-06You have n boxes. You are given a binary string boxes of length n, where boxes[i] is '0' if the ith box is empty, and '1' if it contains one ball.In one operation, you can move one ball from a box to an adjacent box. Box i is adjacent to box j if abs(i - j)..

https://leetcode.com/problems/number-of-ways-to-split-array/description/?envType=daily-question&envId=2025-01-03You are given a 0-indexed integer array nums of length n.nums contains a valid split at index i if the following are true:The sum of the first i + 1 elements is greater than or equal to the sum of the last n - i - 1 elements.There is at least one element to the right of i. That is, 0 R..

https://leetcode.com/problems/count-vowel-strings-in-ranges/description/?envType=daily-question&envId=2025-01-02You are given a 0-indexed array of strings words and a 2D array of integers queries.Each query queries[i] = [li, ri] asks us to find the number of strings present in the range li to ri (both inclusive) of words that start and end with a vowel.Return an array ans of size queries.length,..

https://leetcode.com/problems/minimum-cost-for-tickets/description/?envType=daily-question&envId=2024-12-31You have planned some train traveling one year in advance. The days of the year in which you will travel are given as an integer array days. Each day is an integer from 1 to 365.Train tickets are sold in three different ways:a 1-day pass is sold for costs[0] dollars,a 7-day pass is sold for..

https://leetcode.com/problems/count-ways-to-build-good-strings/description/?envType=daily-question&envId=2024-12-30Given the integers zero, one, low, and high, we can construct a string by starting with an empty string, and then at each step perform either of the following:Append the character '0' zero times.Append the character '1' one times.This can be performed any number of times.A good stri..

https://leetcode.com/problems/maximum-frequency-stack/description/Design a stack-like data structure to push elements to the stack and pop the most frequent element from the stack.Implement the FreqStack class:FreqStack() constructs an empty frequency stack.void push(int val) pushes an integer val onto the top of the stack.int pop() removes and returns the most frequent element in the stack.If t..

https://leetcode.com/problems/best-sightseeing-pair/description/?envType=daily-question&envId=2024-12-27You are given an integer array values where values[i] represents the value of the ith sightseeing spot. Two sightseeing spots i and j have a distance j - i between them.The score of a pair (i  values[i] + values[j] + i - j: the sum of the values of the sightseeing spots, minus the distance bet..

https://leetcode.com/problems/target-sum/description/?envType=daily-question&envId=2024-12-26You are given an integer array nums and an integer target.You want to build an expression out of nums by adding one of the symbols '+' and '-' before each integer in nums and then concatenate all the integers.For example, if nums = [2, 1], you can add a '+' before 2 and a '-' before 1 and concatenate the..