diff --git a/1603. Design Parking System/README.md b/1603. Design Parking System/README.md
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+# 1603. Design Parking System
+
+[Design Parking System](https://leetcode.com/problems/design-parking-system/)
+
+## 김시현 - 2023.05.29
+
+- 클래스 내 메소드 구현
+- carType이 정수 1,2,3으로 입력받아서 배열의 index로 이용하면 편할 것 같아서 park 배열을 선언하고 값을 넣어줬다.
+- 배열의 값이 0보다 크기만 하면 공간이 있다는 뜻이므로 true를 return한다.
+- park배열을 ParkingSystem에서 한 번에 초기화해서 코드를 더 깔끔하게 수정하였다.
+
+```java
+class ParkingSystem {
+        int[] park;
+
+    public ParkingSystem(int big, int medium, int small) {
+        park = new int[] {big, medium, small};
+    }
+    
+    public boolean addCar(int carType) {
+        return park[carType - 1]-- > 0;
+    }
+}
+```
diff --git a/1732. Find the Highest Altitude/README.md b/1732. Find the Highest Altitude/README.md
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+# 1732. Find the Highest Altitude
+
+[Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target/)
+
+## 김시현 - 2023.06.19
+
+- for문 돌면서 sum에 더하여 저장, sum이 max보다 큰 경우 바꿔줌
+
+```java
+class Solution {
+    public int largestAltitude(int[] gain) {
+        int sum = 0, max = 0;
+        for(int i = 0; i < gain.length; i++) {
+            sum += gain[i];
+            max = Math.max(sum, max);
+        }
+        return max;
+    }
+}
+```
diff --git a/2490. Circular Sentence/README.md b/2490. Circular Sentence/README.md
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+# 2490. Circular Sentence
+
+[Circular Sentence](https://leetcode.com/problems/circular-sentence/)
+
+## 김시현 - 2023.06.29
+
+- sentence를 공백으로 나누어 String 배열에 넣어주고 for문 돌면서
+마지막 문자와 다음 String 첫 문자를 비교해준다.
+
+```java
+class Solution {
+    public boolean isCircularSentence(String sentence) {
+        String[] str = sentence.split(" ");
+        for(int i = 0; i < str.length; i++) {
+            if(str[i].charAt(str[i].length() - 1)
+            != str[(i + 1) % str.length].charAt(0))
+                return false;
+        }
+        return true;
+    }
+} 
+```
diff --git a/744. Find Smallest Letter Greater Than Target/README.md b/744. Find Smallest Letter Greater Than Target/README.md
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+# 744. Find Smallest Letter Greater Than Target
+
+[Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target/)
+
+## 김시현 - 2023.06.09
+
+- letters배열에 for문 돌면서 저장된 아스키코드값을 비교해 target보다 크면 return
+- 배열에 더 큰 값이 없다면 letters[0] return
+
+```java
+class Solution {
+    public char nextGreatestLetter(char[] letters, char target) {
+        for(var c: letters) if(c > target) return c;
+        return letters[0];
+    }
+}
+```