diff --git a/doitchuu/BinarySearch.js b/doitchuu/BinarySearch.js
new file mode 100644
index 0000000..c9329d9
--- /dev/null
+++ b/doitchuu/BinarySearch.js
@@ -0,0 +1,27 @@
+function search(nums, target) {
+  return nums.indexOf(target);
+}
+
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
+var search = function (nums, target) {
+  let start = 0;
+  let end = nums.length - 1;
+
+  while (start <= end) {
+    const middle = Math.floor((start + end) / 2);
+
+    if (nums[middle] === target) {
+      return middle;
+    } else if (nums[middle] > target) {
+      end = middle - 1;
+    } else {
+      start = middle + 1;
+    }
+  }
+
+  return -1;
+};
diff --git a/doitchuu/FloodFill.js b/doitchuu/FloodFill.js
new file mode 100644
index 0000000..2f5123f
--- /dev/null
+++ b/doitchuu/FloodFill.js
@@ -0,0 +1,30 @@
+var floodFill = function (image, sr, sc, color) {
+  const dx = [-1, 0, 1, 0];
+  const dy = [0, 1, 0, -1];
+
+  const original = image[sr][sc];
+  if (original === color) return image;
+
+  const rows = image.length;
+  const cols = image[0].length;
+
+  const queue = [[sr, sc]];
+  image[sr][sc] = color; // 방문 처리(색칠) 먼저
+
+  while (queue.length) {
+    const [x, y] = queue.shift();
+
+    for (let dir = 0; dir < 4; dir++) {
+      const nx = x + dx[dir];
+      const ny = y + dy[dir];
+
+      if (nx < 0 || ny < 0 || nx >= rows || ny >= cols) continue;
+      if (image[nx][ny] !== original) continue;
+
+      image[nx][ny] = color;
+      queue.push([nx, ny]);
+    }
+  }
+
+  return image;
+};
diff --git a/doitchuu/InvertBinaryTree.js b/doitchuu/InvertBinaryTree.js
new file mode 100644
index 0000000..92fc411
--- /dev/null
+++ b/doitchuu/InvertBinaryTree.js
@@ -0,0 +1,12 @@
+function invertTree(root) {
+  if (root === null) return null;
+
+  const temp = root.left;
+  root.left = root.right;
+  root.right = temp;
+
+  invertTree(root.left);
+  invertTree(root.right);
+
+  return root;
+}
diff --git a/doitchuu/ValidAnagram.js b/doitchuu/ValidAnagram.js
new file mode 100644
index 0000000..d320589
--- /dev/null
+++ b/doitchuu/ValidAnagram.js
@@ -0,0 +1,32 @@
+/**
+ * @param {string} s
+ * @param {string} t
+ * @return {boolean}
+ */
+var isAnagram = function (s, t) {
+  if (s.length !== t.length) {
+    return false;
+  }
+
+  const sMap = new Map();
+  const tMap = new Map();
+
+  for (let i = 0; i < s.length; i++) {
+    sMap.set(s[i], (sMap.get(s[i]) ?? 0) + 1);
+    tMap.set(t[i], (tMap.get(t[i]) ?? 0) + 1);
+  }
+
+  for (const [key, value] of sMap) {
+    const tValue = tMap.get(key);
+
+    if (tValue === undefined) {
+      return false;
+    }
+
+    if (tValue !== value) {
+      return false;
+    }
+  }
+
+  return true;
+};