diff --git "a/leetcode3/\354\227\274\355\230\234\354\240\225/1034. Coloring A Border.java" "b/leetcode3/\354\227\274\355\230\234\354\240\225/1034. Coloring A Border.java"
new file mode 100644
index 00000000..cf3f056f
--- /dev/null
+++ "b/leetcode3/\354\227\274\355\230\234\354\240\225/1034. Coloring A Border.java"	
@@ -0,0 +1,46 @@
+// dfs
+
+class Solution {
+
+    boolean[][] isVisited;
+    int[] dr = {-1, 1, 0, 0};
+    int[] dc = {0, 0, -1, 1};
+
+    public int[][] colorBorder(int[][] grid, int row, int col, int color) {
+        isVisited = new boolean[grid.length][grid[0].length];
+
+        List<int[]> borders = new ArrayList<>();
+        dfs (grid, row, col, grid[row][col], borders);
+
+        for (int[] b : borders) {
+            grid[b[0]][b[1]] = color;
+        }
+
+        return grid;
+    }
+
+    void dfs(int[][] grid, int row, int col, int gridColor, List<int[]> borders) {
+        isVisited[row][col] = true;
+
+        boolean isBorder = false;
+        for (int i = 0; i<4; i++) {
+            int nr = row + dr[i];
+            int nc = col + dc[i];
+
+            if (nr<0 || nr>=grid.length || nc<0 || nc>=grid[0].length) { // 테두리
+                isBorder = true;
+                continue;
+            }
+
+            if (grid[nr][nc] != gridColor) {
+                isBorder = true;
+                continue;
+            }
+
+            if (!isVisited[nr][nc]) {
+                dfs(grid, nr, nc, gridColor, borders);
+            }
+        }
+        if (isBorder) borders.add(new int[]{row, col});
+    }
+}
diff --git "a/leetcode3/\354\227\274\355\230\234\354\240\225/3838. Weighted Word Mapping.java" "b/leetcode3/\354\227\274\355\230\234\354\240\225/3838. Weighted Word Mapping.java"
new file mode 100644
index 00000000..2535455a
--- /dev/null
+++ "b/leetcode3/\354\227\274\355\230\234\354\240\225/3838. Weighted Word Mapping.java"	
@@ -0,0 +1,17 @@
+// 97 ~ 122
+
+class Solution {
+    public String mapWordWeights(String[] words, int[] weights) {
+        StringBuilder sb = new StringBuilder();
+        for (String word : words) {
+            int sum = 0;
+            for (char c : word.toCharArray()) {
+                int num = (int) c - 97;
+                sum += weights[num];
+            }
+            int mod = sum % 26;
+            sb.append((char)('z' - mod));
+        }
+        return sb.toString();
+    }
+}
diff --git "a/leetcode3/\354\227\274\355\230\234\354\240\225/3978. Unique Middle Element.java" "b/leetcode3/\354\227\274\355\230\234\354\240\225/3978. Unique Middle Element.java"
new file mode 100644
index 00000000..d15098db
--- /dev/null
+++ "b/leetcode3/\354\227\274\355\230\234\354\240\225/3978. Unique Middle Element.java"	
@@ -0,0 +1,11 @@
+class Solution {
+    public boolean isMiddleElementUnique(int[] nums) {
+        int middle = (nums.length - 1) / 2;
+        int cnt = 0;
+        for (int num : nums) {
+            if (num == nums[middle]) cnt++;
+            if (cnt == 2) break;
+        }
+        return cnt == 1;
+    }
+}