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Given an array of integers temperatures represents the daily temperatures, return an array answer such that answer[i] is the number of days you have to wait after the ith day to get a warmer temperature. If there is no future day for which this is possible, keep answer[i] == 0 instead.주어진 온도 배열에서, 각 날 이후 더 따뜻한 날이 오기까지 며칠을 기다려야 하는지 계산하는 문제이다. 풀이1: 브루트 포스class Solution: def dailyTemperatures(s..

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.Example 1:Input: n = 3 Output: ["((()))","(()())","(())()","()(())","()()()"] n 이라는 limit이 있으면,여는 괄호 수를 openN, 닫는 괄호 수를 closeN이라고 했을 때closeN closeN > openN이 되면 well-formed parentheses가 되지 못하기 때문이다. 아래와 같이 트리 구조를 그려보며 가능한 경우의 수를 생각해볼 수 있다.  풀이1: 백트래킹, stack 이용class Solution: def generateParen..

Postfix NotationYou are given an array of strings tokens that represents an arithmetic expression in a Reverse Polish Notation.Evaluate the expression. Return an integer that represents the value of the expression.Note that:The valid operators are '+', '-', '*', and '/'.Each operand may be an integer or another expression.The division between two integers always truncates toward zero.There will ..

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.Implement the MinStack class:- MinStack() initializes the stack object.- void push(int val) pushes the element val onto the stack.- void pop() removes the element on the top of the stack.- int top() gets the top element of the stack.- int getMin() retrieves the minimum element in the stack.You must i..

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.Every close bracket has a corresponding open bracket of the same type.괄호가 올바르게 짝지어졌는지 확인하는 문제! 풀이1: Stack 이용class Solution: def isValid(sel..