diff --git a/src/programmers/Lv_2/README.md b/src/programmers/Lv_2/README.md
index 31c8beea..55336a08 100644
--- a/src/programmers/Lv_2/README.md
+++ b/src/programmers/Lv_2/README.md
@@ -101,5 +101,5 @@
 | 97  | [석유 시추](./oil.js)                            | 24.01.24 |     X     |
 | 98  | [당구 연습](./billiard.js)                       | 24.01.26 |     X     |    [24.03.13](./replay/billiard.js)     |
 | 99  | [순위 검색](./search.js)                         | 24.01.27 |     X     |
-| 100 | [혼자서 하는 틱택토](./alone.js)                 | 24.02.07 |     X     |
+| 100 | [혼자서 하는 틱택토](./alone.js)                 | 24.02.07 |     X     |      [24.03.14](./replay/alone.js)      |
 | 101 | [테이블 해시 함수](./tableHash.js)               | 24.03.08 |     X     |       [24.03.12](./tableHash.js)        |
diff --git a/src/programmers/Lv_2/replay/alone.js b/src/programmers/Lv_2/replay/alone.js
new file mode 100644
index 00000000..c34cc332
--- /dev/null
+++ b/src/programmers/Lv_2/replay/alone.js
@@ -0,0 +1,42 @@
+/**
+ * [구현]
+ */
+
+function checkTicTacToe(board, sign) {
+  const lines = [
+    [0, 1, 2],
+    [3, 4, 5],
+    [6, 7, 8],
+    [0, 3, 6],
+    [1, 4, 7],
+    [2, 5, 8],
+    [0, 4, 8],
+    [2, 4, 6],
+  ];
+
+  for (const [a, b, c] of lines) {
+    if (board[a] == sign && board[b] == sign && board[c] == sign) return true;
+  }
+  return false;
+}
+
+function solution(board) {
+  board = board.map((value) => value.split("")).flat();
+  let [O, X] = [0, 0];
+
+  for (const sign of board) {
+    if (sign === "O") O++;
+    else if (sign === "X") X++;
+  }
+
+  if (O < X || 1 < O - X) return 0;
+
+  let oWins = checkTicTacToe(board, "O");
+  let xWins = checkTicTacToe(board, "X");
+
+  if (oWins && xWins) return 0;
+  if (oWins && O - X !== 1) return 0;
+  if (xWins && O !== X) return 0;
+
+  return 1;
+}