[21주차] 이지영

BOJ/1000-5000번/JY_2170.java

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+import java.io.*;
+import java.util.*;
+public class JY_2170 {
+
+	static class Pos implements Comparable<Pos> {
+		int x, y;
+
+		public Pos(int x, int y) {
+			super();
+			this.x = x;
+			this.y = y;
+		}
+		@Override
+		public int compareTo(Pos other) {
+			return this.x - other.x;
+		}
+
+		@Override
+		public String toString() {
+			return "Pos [x=" + x + ", y=" + y + "]";
+		}
+
+	}
+
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		StringTokenizer st = new StringTokenizer(br.readLine());
+
+		int N = Integer.parseInt(st.nextToken());
+
+		List<Pos> pList = new ArrayList<>();
+		for(int i=0; i<N; i++) {
+			st = new StringTokenizer(br.readLine());
+			int x = Integer.parseInt(st.nextToken());
+			int y = Integer.parseInt(st.nextToken());
+
+			pList.add(new Pos(x, y));
+		}
+
+		// x기준으로 정렬
+		Collections.sort(pList);
+
+		int s = pList.get(0).x;
+		int e = pList.get(0).y;
+		int ans = 0;
+		for(int i=1; i<N; i++) {
+			Pos now = pList.get(i);
+
+			// now.x가 end보다 작다면 겹침 -> end 갱신
+			if(e >= now.x) {
+				e = Math.max(e, now.y);
+			}
+			// 겹치지 않는 경우
+			else {
+				// 기존것 더해주고 새로 업데이트
+				ans += (e - s);
+				s = now.x;
+				e = now.y;
+			}
+		}
+		ans += (e - s);
+		System.out.println(ans);
+
+	}
+
+}

BOJ/1000-5000번/JY_2504.java

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+import java.io.*;
+import java.util.*;
+public class JY_2504 {
+
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+		String line = br.readLine();
+
+		Stack<Character> stack = new Stack<>();
+
+		int ans = 0;
+		int tmp = 1;
+		for(int i=0; i<line.length(); i++) {
+			char ch = line.charAt(i);
+			// 열린괄호
+			if(ch == '(') {
+				stack.push(ch);
+				tmp *= 2;
+			} else if(ch == '[') {
+				stack.push(ch);
+				tmp *= 3;
+			}
+			// 닫힌 괄호
+			else {
+				if(stack.isEmpty()) {
+					ans = 0;
+					break;
+				}
+				// 올바르지 않은 괄호
+				if((ch == ')' && stack.peek() == '[') || (ch == ']' && stack.peek() =='(')) {
+					ans = 0;
+					break;
+				}
+				// 이전 값이 올바른 괄호라면 값 저장
+				if(ch == ')') {
+					if(line.charAt(i-1)=='(') ans += tmp;
+					tmp /= 2;
+				} else {
+					if(line.charAt(i-1)=='[') ans += tmp;
+					tmp /= 3;
+				}
+				stack.pop();
+			}
+		}
+
+		if(!stack.isEmpty()) System.out.println(0);
+		else System.out.println(ans);
+	}
+
+}

SQL/21주차/JY_FrontEnd_개발자_찾기.sql

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+-- https://school.programmers.co.kr/learn/courses/30/lessons/276035
+-- FrontEnd 개발자 찾기
+SELECT DISTINCT A.ID, A.EMAIL, A.FIRST_NAME, A.LAST_NAME
+FROM DEVELOPERS A
+JOIN SKILLCODES B
+ON A.SKILL_CODE & B.CODE = B.CODE
+WHERE CATEGORY = "Front End"
+ORDER BY A.ID