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My Tech Blog (๋ฉ”์†Œ๋“œ)

๐Ÿ“‘ 1. ๋ฌธ์ž์—ด ์„ž๊ธฐ ๐Ÿ’ก 1-1. ์ ‘๊ทผ๋ฐฉ์‹โ–  ๋‹จ์ˆœํžˆ ์ฃผ์–ด์ง„ ๋ณ€์ˆ˜๋ช… ๊ทธ๋Œ€๋กœ a + b > b + a ์ด๋ ‡๊ฒŒ ๋น„๊ตํ•˜๋ฉด ๋‘ ์ˆซ์ž๋Š” ์ •์ˆ˜ ๋ง์…ˆ์ด๊ธฐ ๋•Œ๋ฌธ์— ํ•ญ์ƒ a + b == b + a๊ฐ€ ๋œ๋‹ค. ๋ฌธ์ œ์—์„œ ์˜๋„ํ•œ ๊ฒƒ์€ ์ˆซ์ž๋ฅผ ๋ฌธ์ž์—ด๋กœ ๋ณ€ํ™˜ํ•˜์—ฌ ์—ฐ๊ฒฐํ•œ ํ›„, ํฌ๊ธฐ๋ฅผ ๋น„๊ตํ•˜๋Š” ๊ฒƒ์ด๋‹ค. ์˜ฌ๋ฐ”๋ฅด๊ฒŒ ๋น„๊ตํ•˜๋ ค๋ฉด String.valueOf(a) + b์™€ String.valueOf(b) + a ๋ฅผ ๋น„๊ตํ•ด์•ผ ํ•œ๋‹ค.  โ–   ๋˜ ๋‚˜๋Š” ์ฒ˜์Œ์— sb.toString()์„ ์จ์„œ int๋กœ ๋ฐ˜ํ™˜ํ•˜๋Š” ์‹ค์ˆ˜๋ฅผ ํ–ˆ๋Š”๋ฐ,  sb.toString()์€ ๋ฌธ์ž์—ด์ด๊ธฐ ๋•Œ๋ฌธ์—, int ํƒ€์ž…์„ ๋ฐ˜ํ™˜ํ•˜๋Š” solution ๋ฉ”์„œ๋“œ์™€ ํƒ€์ž…์ด ๋งž์ง€ ์•Š๋Š”๋‹ค. ๊ทธ๋ž˜์„œ Integer.parseInt(sb.toString())์„ ์‚ฌ์šฉํ•˜์—ฌ ๋ณ€ํ™˜ํ•ด์•ผ ํ•œ๋‹ค.  ํ‹€๋ฆฐ ์ฝ”๋“œclas..
๐Ÿ“‘ 1. ๋ฌธ์ œ์„ค๋ช… ๐Ÿ’ก 2. ์ •๋‹ต์ฝ”๋“œ๐Ÿ™…๐Ÿป‍โ™€๏ธ ์ฒซ ๋ฒˆ์งธ ์‹œ๋„ - ํ‹€๋ฆผ โŒํ”„๋กœ๊ทธ๋ž˜๋จธ์Šค ์ฝ˜์†”์ด ์ž๋™์™„์„ฑ์ด ์•ˆ ๋˜๊ธฐ ๋•Œ๋ฌธ์— ์ƒ๊ฐ๋‚˜๋Š”๋ฐ๋กœ ์จ์„œ ๋งŽ์ด ํ‹€๋ ธ๋‹ค.class Solution {    public String solution(String str1, String str2) {        StringBuilder sb = new StringBuilder();        for(int i = 0; i   ์˜ค๋‹ต ์ •๋ฆฌโญ str1.length → str1.length() length๋Š” ๋ฐฐ์—ด์—์„œ ์‚ฌ์šฉ๋˜๊ณ , ๋ฌธ์ž์—ด์—์„œ๋Š” length() ๋ฉ”์„œ๋“œ๋ฅผ ์‚ฌ์šฉํ•œ๋‹ค. โญ  sb.add(...) → sb.append(...)StringBuilder๋Š” add() ๋ฉ”์„œ๋“œ๊ฐ€ ์—†๊ณ , ๋Œ€์‹  append()๋ฅผ ์‚ฌ์šฉํ•ด์•ผ ํ•œ๋‹ค.โญ  st..
๐Ÿ“‘ 1. ๋ฌธ์ œ์„ค๋ช…โญ 2. ์ •๋‹ต์ฝ”๋“œclass Solution { public String solution(String my_string, String overwrite_string, int s) { // ์•ž๋ถ€๋ถ„๊ณผ ๋’ท๋ถ€๋ถ„์„ ์ถ”์ถœํ•œ ํ›„ overwrite_string์„ ์ค‘๊ฐ„์— ์‚ฝ์ž… String before = my_string.substring(0, s); String after = my_string.substring(s + overwrite_string.length()); return before + overwrite_string + after; }} โญ String before = my_string.substring(0, s); ์—์„œ substr..
์ „๋ถ€ํ„ฐ ํฌ์ŠคํŒ… ํ•ด์•ผ ๊ฒ ๋‹ค๊ณ  ์ƒ๊ฐํ–ˆ๋Š”๋ฐ ๋ฏธ๋ฃจ๋‹ค๊ฐ€ ํ•˜๋Š” ํฌ์ŠคํŒ… ์ž๋ฃŒ์กฐ์‚ฌ ํ•˜๋ ค๋ฉด ๋„ˆ๋ฌด ์˜ค๋ž˜๊ฑธ๋ ค์„œ ๋‹ค์Œ์— ํ•˜๋ ค๋‹ค๊ฐ€ ์ง€๊ธˆ ์งฌ๋‚ด์„œ ํ›„๋”ฑ ํ•ด ๋ฒ„๋ฆฌ์ž  1. Map๊ณผ Set Map๊ณผ Set์€ ์ž๋ฐ”์—์„œ ์ปฌ๋ ‰์…˜ ํ”„๋ ˆ์ž„์›Œํฌ(Collection Framework)์— ์†ํ•˜๋Š” ์ž๋ฃŒ๊ตฌ์กฐ์ด๋‹ค. ๋‘˜ ๋‹ค java.utilํŒจํ‚ค์ง€์— ํฌํ•จ๋˜์–ด ์žˆ๋‹ค. ๊ธฐ๋ณธ ์ž๋ฃŒํ˜•์€ ์•„๋‹ˆ๊ณ  ๊ฐ์ฒด๋กœ ๋‹ค๋ฃจ์–ด์ง€๋Š” ์ž๋ฃŒ๊ตฌ์กฐ์ธ๋ฐ, Map์€ key-value ํ˜•ํƒœ๋กœ ๋น ๋ฅธ ๊ฒ€์ƒ‰์ด ํ•„์š”ํ•œ ๋Œ€๋Ÿ‰์˜ ๋ฐ์ดํ„ฐ๋ฅผ ๋‹ค๋ฃฐ ๋•Œ ์œ ์šฉํ•˜๊ณ , Set์€ ์ค‘๋ณต ์—†๋Š” ๋ฐ์ดํ„ฐ ์ง‘ํ•ฉ์ด ํ•„์š”ํ•  ๋•Œ ์‚ฌ์šฉ๋œ๋‹ค.   2. Map ์ด๋ž€? ์‚ฌ๋žŒ์„ ‘์ด๋ฆ„ = ์ตœ๋‹ค์ธ’, 'ํ‚ค = 165' ๋“ฑ์œผ๋กœ ๊ตฌ๋ถ„ํ•  ์ˆ˜ ์žˆ๋“ฏ์ด ๋งต(Map) ์€ ๋Œ€์‘ ๊ด€๊ณ„๋ฅผ ์‰ฝ๊ฒŒ ํ‘œํ˜„ํ•  ์ˆ˜ ์žˆ๊ฒŒ ํ•ด์ฃผ๋Š” ์ž๋ฃŒํ˜•์ด๋‹ค. ๋งต์˜ ๊ตฌํ˜„์ฒด ์ค‘์— ๊ฐ€์žฅ ์œ ๋ช…ํ•œ ๊ฑด ..
์•„.... ๊ณต๋ถ€ํ•˜๋‹ค๊ฐ€ ๋‚˜๋งŒ ๋ณด๋ ค๊ณ  ์ด๋ ‡๊ฒŒ ์ž์„ธํ•˜๊ฒŒ ์ ์„ ์ƒ๊ฐ ์—†์—ˆ๋Š”๋ฐ ํ˜น์‹œ๋‚˜์ œ ๋ธ”๋กœ๊ทธ ๋“ค์–ด์˜ค์‹ค ์ˆ˜๋„ ์žˆ๋Š” ๋ถ„๋“ค์„ ์œ„ํ•ด์„œ... ๊ทธ๋ƒฅ ๋‹ค ์š”์•ฝํ•ด์„œ ์ ์–ด ๋ด…๋‹ˆ๋‹ค..ใ…‹ใ…‹ใ…‹ ํŒŒ์ด์ฌ์˜ ์ž๋ฃŒ ๊ตฌ์กฐ ๋ฆฌ์ŠคํŠธ [ ]Square BracketSํŠœํ”Œ ( )Round Brackets์…‹ { }Braces๋”•์…”๋Ÿฌ๋‹ˆ { 'key:value' }  1. ๋ฆฌ์ŠคํŠธ(List)  - ๋ฐฐ์—ด์ฒ˜๋Ÿผ ์—ฌ๋Ÿฌ ์š”์†Œ๋ฅผ ๊ฐ–๋Š” ์ง‘ํ•ฉ,  - ์ƒˆ๋กœ์šด ์š”์†Œ ์‚ฝ์ž…, ๊ฐฑ์‹ , ์‚ญ์ œ ๊ฐ€๋Šฅ - ํŒŒ์ด์ฌ ๋ฆฌ์ŠคํŠธ๋Š” ๋™์  ๋ฐฐ์—ด, ์ฆ‰ ์ž์œ ๋กญ๊ฒŒ ํ™•์žฅ ๊ฐ€๋Šฅ - [] ๋Œ€๊ด„ํ˜ธ ์‚ฌ์šฉ - ๊ฐ ์š”์†Œ๋“ค์€ ์„œ๋กœ ๋‹ค๋ฅธ ํƒ€์ž…๋„ ๊ฐ€๋Šฅ โœ… ๋ฆฌ์ŠคํŠธ ๋ฉ”์„œ๋“œ - # list.index(์š”์†Œ) ๋ฆฌ์ŠคํŠธ์—์„œ ํŠน์ • ์š”์†Œ ์œ„์น˜ ๊ฒ€์ƒ‰ - ์ฒซ๋ฒˆ์งธ ์‹œ์ž‘ํ•˜๋Š” ์œ„์น˜ ๋ฐ˜ํ™˜- # list.count(์š”์†Œ) ๋ฆฌ์ŠคํŠธ ์•ˆ์— ์œ„์น˜๊ฐ€ ํฌํ•จ๋œ..
๐Ÿ“ JavaScript โœ… 1. screen ๊ฐ์ฒดscreen ๊ฐ์ฒด๋Š” ์‚ฌ์šฉ์ž์˜ ๋ชจ๋‹ˆํ„ฐ ์ •๋ณด(์†์„ฑ)์„ ์ œ๊ณตํ•˜๋Š” ๊ฐ์ฒด์ž…๋‹ˆ๋‹ค. ์˜ˆ๋ฅผ ๋“ค์–ด ๋ชจ๋‹ˆํ„ฐ์˜ ๋„ˆ๋น„๋‚˜ ๋†’์ด ๋˜๋Š” ์ปฌ๋Ÿฌ ํ‘œํ˜„ bit์„ ๋ฐ˜ํ™˜ํ•ฉ๋‹ˆ๋‹ค.  1-1. ๊ธฐ๋ณธํ˜• screen.์†์„ฑ;screen.width; //๋ชจ๋‹ˆํ„ฐ์˜ ๋„ˆ๋น—๊ฐ’ ๋ฐ˜ํ™˜ 1-2. screen ๊ฐ์ฒด ์˜ ์†์„ฑ ์ข…๋ฅ˜์ข…๋ฅ˜์„ค๋ช…screen.widthํ™”๋ฉด์˜ ๋„ˆ๋น„๊ฐ’ ๋ฐ˜ํ™˜screen.heightํ™”๋ฉด์˜ ๋†’์ด๊ฐ’ ๋ฐ˜ํ™˜screen.availWidth(์ž‘์—… ํ‘œ์‹œ์ค„์„ ์ œ์™ธํ•œ) ํ™”๋ฉด์˜ ๋„ˆ๋น„๊ฐ’ ๋ฐ˜ํ™˜ screen.availHeight (์ž‘์—… ํ‘œ์‹œ์ค„์„ ์ œ์™ธํ•œ) ํ™”๋ฉด์˜ ๋†’์ด๊ฐ’ ๋ฐ˜ํ™˜ screen.colorDepth์‚ฌ์šฉ์ž ๋ชจ๋‹ˆํ„ฐ๊ฐ€ ํ‘œํ˜„ ๊ฐ€๋Šฅํ•œ ์ปฌ๋Ÿฌ bit๋ฅผ ๋ฐ˜ํ™˜  โœ… 2. location ๊ฐ์ฒดlocation ๊ฐ์ฒด๋Š” ์‚ฌ์šฉ์ž ๋ธŒ๋ผ์šฐ์ €์™€ ๊ด€๋ จ..
โœ… ๋ฌธ์ œ2๊ฐœ์˜ ์ •์ˆ˜ base, n์„ ์ž…๋ ฅ ๋ฐ›๊ธฐbase์˜ n์ œ๊ณฑ ๋ฐ˜ํ™˜ํ•˜๋Š” powerN() ๋ฉ”์†Œ๋“œ ๋งŒ๋“ค๊ธฐโœ… ์ฝ”๋“œpublic class bonus06 { public static void main(String[] args) { System.out.println(powerN(2, 3)); } public static int powerN(int base, int n) { int result = 1; for (int i = 0; i  ๋ฉ”์„œ๋“œ๋Š” Main ์˜์—ญ ๋ฐ–์—์„œ ๋งŒ๋“ค์–ด ์ค€๋‹ค.๋งค๊ฐœ๋ณ€์ˆ˜ 2 ๊ฐœ: base์™€ nresult ๋ณ€์ˆ˜๋ฅผ 1๋กœ ์ดˆ๊ธฐํ™” (๊ฒฐ๊ณผ ์ €์žฅํ•  ๋ณ€์ˆ˜)for ๋ฃจํ”„๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ base๋ฅผ n๋ฒˆ ๊ณฑํ•œ๋‹ค. ๋ฃจํ”„๊ฐ€ ํ•œ ๋ฒˆ ์‹คํ–‰๋  ๋•Œ๋งˆ๋‹ค result์— base๋ฅผ ๊ณฑํ•ด..
โœ… ๋ฌธ์ œ๊ณ„์‚ฐ๊ธฐ ๋งŒ๋“ค๊ธฐ โœ… ์ถ”๋ก  ๊ณผ์ • ๋‘ ๊ฐœ์˜ ์ •์ˆ˜์™€ ์—ฐ์‚ฐ์ž๋ฅผ ์ž…๋ ฅ ๋ฐ›์•„์„œ ํ•ด๋‹น ์—ฐ์‚ฐ์„ ์ˆ˜ํ–‰ํ•˜๋Š” ๊ฐ„๋‹จํ•œ ๊ณ„์‚ฐ๊ธฐ ๊ตฌํ˜„ ์ฝ”๋“œ์ด๋‹ค. ๋งค๊ฐœ๋ณ€์ˆ˜๊ฐ€ ์ด 3๊ฐœ์ด๊ณ , int ํ˜•์œผ๋กœ ๊ฒฐ๊ณผ๋ฅผ return ํ•ด ์ฃผ๋ฉด ๋˜๋Š” ์‰ฌ์šด ๋ฌธ์ œ์ด๋‹ค. ๋ฉ”์„œ๋“œ๋Š” Main ์˜์—ญ ๋ฐ–์—์„œ ๋งŒ๋“ค์–ด์ฃผ๊ณ  ๊ฒฐ๊ณผ ๊ฐ’๋งŒ Main ์˜์—ญ ์•ˆ์—์„œ ์ถœ๋ ฅํ•ด์ฃผ๋ฉด ๋œ๋‹ค. โœ… ์ฝ”๋“œpublic class bonus03 { public static void main(String[] args) { System.out.println(cal(4, 7, '*')); } public static int cal(int num1, int num2, char op) { if (op == '+') { return n..
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