방구석 개발자의 실험실

[CORS] CORS 개념과 스프링 부트에서 처리하는 방법(OPTIONS 요청)

1. CORS 란?Cross-Origin Resource Sharing 의 약자로, 웹 브라우저에서 다른 출처(도메인, 프로토콜, 포트)의 리소스에 접근할 수 있도록 허용하는 메커니즘FE(브라우저) → BE(API 서버) 요청을 할 때, 도메인/포트/프로토콜이 다르면 "Cross-Origin" 요청이 됩니다.보안 때문에 브라우저는 기본적으로 이를 차단해요.서버가 **“나는 이 출처(origin)에서 오는 요청을 허용한다”**라고 응답해줘야 브라우저가 통과시킵니다.=> 한마디로 말해서, BE API를 아무나 호출할 수 없도록 브라우저 보안 표준상 CORS 에러를 발생시켜 차단.=> 개발계에서는 편하려고 * 열어두고(모든 도메인에서 오는 요청을 다 허용), 운영계에서는 필요한 출처만 허용해둠.Access-C..

[해커랭크] Extra Long Factorials https://www.hackerrank.com/challenges/extra-long-factorials/problem?isFullScreen=true Extra Long Factorials | HackerRankCalculate a very large factorial that doesn't fit in the conventional numeric data types.www.hackerrank.com The factorial of the integer , written , is defined as: Calculate and print the factorial of a given integer.For example, if , we calculate ..

[해커랭크] Utopian Treehttps://www.hackerrank.com/challenges/utopian-tree/problem?isFullScreen=true Utopian Tree | HackerRankPredict the height of the tree after N growth cycles.www.hackerrank.com The Utopian Tree goes through 2 cycles of growth every year. Each spring, it doubles in height. Each summer, its height increases by 1 meter.A Utopian Tree sapling with a height of 1 meter is planted at th..

https://www.hackerrank.com/challenges/designer-pdf-viewer/problem?isFullScreen=true Designer PDF Viewer | HackerRankHelp finding selection area in PDF Viewer.www.hackerrank.com When a contiguous block of text is selected in a PDF viewer, the selection is highlighted with a blue rectangle. In this PDF viewer, each word is highlighted independently. For example:There is a list of character h..

[해커랭크] The Hurdle Racehttps://www.hackerrank.com/challenges/the-hurdle-race/problem?isFullScreen=true= 0." data-og-host="www.hackerrank.com" data-og-source-url="https://www.hackerrank.com/challenges/the-hurdle-race/problem?isFullScreen=true" data-og-url="https://www.hackerrank.com/challenges/the-hurdle-race/problem" data-og-image="https://scrap.kakaocdn.net/dn/dKRyz2/hyZuHOizvE/TVca6Q4SVpvHH5CC9..

[해커랭크] Climbing the Leaderboardhttps://www.hackerrank.com/challenges/climbing-the-leaderboard/problem?isFullScreen=true Climbing the Leaderboard | HackerRankHelp Alice track her progress toward the top of the leaderboard!www.hackerrank.com An arcade game player wants to climb to the top of the leaderboard and track their ranking. The game uses Dense Ranking, so its leaderboard works like this:T..

Given an array of integers, find the longest subarray where the absolute difference between any two elements is less than or equal to .Example There are two subarrays meeting the criterion: and . The maximum length subarray has elements.Function DescriptionComplete the pickingNumbers function in the editor below.pickingNumbers has the following parameter(s):int a[n]: an array of integersReturn..

[해커랭크] Forming a Magic SquareWe define a magic square to be an matrix of distinct positive integers from to where the sum of any row, column, or diagonal of length is always equal to the same number: the magic constant.You will be given a matrix of integers in the inclusive range . We can convert any digit to any other digit in the range at cost of . Given , convert it into a magic square at min..

[해커랭크] Stone DivisionConsider the following game:There are two players, First and Second, sitting in front of a pile of stones. First always plays first.There is a set, , of distinct integers defined as .The players move in alternating turns. During each turn, a player chooses some and splits one of the piles into exactly smaller piles of equal size. If no exists that will split one of the ..

https://www.hackerrank.com/challenges/fun-game-1/problem?isFullScreen=true Kyle and Mike are bored on a rainy day and decide to pass the time by creating a new game having the following rules:The game starts with two -sized integer arrays, and , and is played by two players, and .The players move in alternating turns, with always moving first. During each move, the current player must choose ..