diff --git a/bangdori/300.js b/bangdori/300.js
new file mode 100644
index 0000000..d5b31ea
--- /dev/null
+++ b/bangdori/300.js
@@ -0,0 +1,34 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var lengthOfLIS = function (nums) {
+  const answer = [nums[0]];
+
+  for (let i = 1; i < nums.length; i++) {
+    if (answer[answer.length - 1] < nums[i]) {
+      answer.push(nums[i]);
+      continue;
+    }
+
+    const pos = upperbound(answer, nums[i]);
+    answer[pos] = nums[i];
+  }
+
+  return answer.length;
+};
+
+function upperbound(nums, target) {
+  let left = 0,
+    right = nums.length - 1;
+
+  while (left < right) {
+    const mid = Math.floor((left + right) / 2);
+
+    if (nums[mid] === target) return mid;
+    if (nums[mid] > target) right = mid;
+    else left = mid + 1;
+  }
+
+  return right;
+}