diff --git "a/leetcode2/1easy/\354\265\234\354\233\220\354\244\200/Q3114.java" "b/leetcode2/1easy/\354\265\234\354\233\220\354\244\200/Q3114.java"
new file mode 100644
index 00000000..d2dfb130
--- /dev/null
+++ "b/leetcode2/1easy/\354\265\234\354\233\220\354\244\200/Q3114.java"
@@ -0,0 +1,51 @@
+package Leetcode;
+
+/*
+1. 아이디어 :
+
+
+2. 시간복잡도 :
+O( )
+
+3. 자료구조/알고리즘 :
+
+ */
+
+public class Q3114 {
+    class Solution {
+        public String findLatestTime(String s) {
+            StringBuilder sb = new StringBuilder();
+            if (s.charAt(0) == '?' && s.charAt(1) == '?') {
+                sb.append("11");
+            } else if (s.charAt(0) == '?') {
+                if (Integer.parseInt((s.charAt(1))+"") >= 2) {
+                    sb.append("0").append(s.charAt(1));
+                } else {
+                    sb.append("1").append(s.charAt(1));
+                }
+            } else if (s.charAt(1) == '?') {
+                if (Integer.parseInt((s.charAt(0))+"") == 0) {
+                    sb.append(s.charAt(0)).append("9");
+                } else {
+                    sb.append(s.charAt(0)).append("1");
+                }
+            } else {
+                sb.append(s.charAt(0) + "" + s.charAt(1));
+            }
+
+            sb.append(":");
+
+            if (s.charAt(3) == '?' && s.charAt(4) == '?') {
+                sb.append("59");
+            } else if (s.charAt(3) == '?') {
+                sb.append("5").append(s.charAt(4));
+            } else if (s.charAt(4) == '?') {
+                sb.append(s.charAt(3)).append("9");
+            } else {
+                sb.append(s.charAt(3) + "" + s.charAt(4));
+            }
+
+            return sb.toString();
+        }
+    }
+}
diff --git "a/leetcode2/2medium/\354\265\234\354\233\220\354\244\200/Q777.java" "b/leetcode2/2medium/\354\265\234\354\233\220\354\244\200/Q777.java"
new file mode 100644
index 00000000..4b6e9738
--- /dev/null
+++ "b/leetcode2/2medium/\354\265\234\354\233\220\354\244\200/Q777.java"
@@ -0,0 +1,57 @@
+package Leetcode;
+
+/*
+1. 아이디어 :
+
+
+2. 시간복잡도 :
+O( )
+
+3. 자료구조/알고리즘 :
+
+ */
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Q777 {
+    class Solution {
+        public boolean canTransform(String start, String result) {
+            int n = start.length();
+
+            // [0/1: left/right, idx]
+            List<int[]> startIdx = new ArrayList<>();
+            List<int[]> resultIdx = new ArrayList<>();
+
+            for (int i=0; i<n; i++) {
+                if (start.charAt(i) == 'L') {
+                    startIdx.add(new int[]{0, i});
+                } else if (start.charAt(i) == 'R') {
+                    startIdx.add(new int[]{1, i});
+                }
+
+                if (result.charAt(i) == 'L') {
+                    resultIdx.add(new int[]{0, i});
+                } else if (result.charAt(i) == 'R') {
+                    resultIdx.add(new int[]{1, i});
+                }
+            }
+
+            // for (var a : startIdx) System.out.print(Arrays.toString(a));
+            // System.out.println();
+            // for (var a : resultIdx) System.out.print(Arrays.toString(a));
+
+            if (startIdx.size() != resultIdx.size()) return false;
+            for (int i=0; i<startIdx.size(); i++) {
+                if (startIdx.get(i)[0] != resultIdx.get(i)[0]) return false;
+
+                if (startIdx.get(i)[0] == 0) { // left
+                    if (startIdx.get(i)[1] < resultIdx.get(i)[1]) return false;
+                } else if (startIdx.get(i)[0] == 1) { // right
+                    if (startIdx.get(i)[1] > resultIdx.get(i)[1]) return false;
+                }
+            }
+            return true;
+        }
+    }
+}