물빠진떡 님의 블로그

문제You may recall that an array arr is a mountain array if and only if:arr.length >= 3There exists some index i (0-indexed) with 0 arr[i + 1] > ... > arr[arr.length - 1]Given an integer array nums​​​, return the minimum number of elements to remove to make nums​​​ a mountain array.요약산 모양으로 왼쪽으로는 감소 오른쪽으로는 증가하는 최장 집합를 찾으면 된다.풀이dfs로 깊게 들어가면서 각 index (idx)에서 1. 이전 0~idx 까지 가장 긴 증가 부분집합의 길이2. 이후 idx..

문제You are given a 0-indexed m x n matrix grid consisting of positive integers.You can start at any cell in the first column of the matrix, and traverse the grid in the following way:From a cell (row, col), you can move to any of the cells: (row - 1, col + 1), (row, col + 1) and (row + 1, col + 1) such that the value of the cell you move to, should be strictly bigger than the value of the current..

문제You are given the root of a binary tree and a positive integer k.The level sum in the tree is the sum of the values of the nodes that are on the same level.Return the kth largest level sum in the tree (not necessarily distinct). If there are fewer than k levels in the tree, return -1.Note that two nodes are on the same level if they have the same distance from the root.요약같은 depth에서 총 합의 크기가 k번..

Given a string `s`, return _the maximum number of unique substrings that the given string can be split into_.You can split string `s` into any list of **non-empty substrings**, where the concatenation of the substrings forms the original string. However, you must split the substrings such that all of them are **unique**.A **substring** is a contiguous sequence of characters within a string.풀이 시간..