diff --git a/Week_02/id_39/LeetCode_1_39.js b/Week_02/id_39/LeetCode_1_39.js
new file mode 100644
index 00000000..c9a18b04
--- /dev/null
+++ b/Week_02/id_39/LeetCode_1_39.js
@@ -0,0 +1,17 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[]}
+ * https://leetcode.com/problems/two-sum/
+ */
+var twoSum = function(nums, target) {
+    let hashTable = [];
+    for (let i = 0; i < nums.length; i++) {
+        let other = target - nums[i];
+        if (hashTable[other] >= 0) {
+            return [hashTable[other], i];
+        };
+        hashTable[nums[i]] = i;
+    }
+    return null;
+};
\ No newline at end of file
diff --git a/Week_02/id_39/LeetCode_242_39.js b/Week_02/id_39/LeetCode_242_39.js
new file mode 100644
index 00000000..559310ef
--- /dev/null
+++ b/Week_02/id_39/LeetCode_242_39.js
@@ -0,0 +1,30 @@
+/**
+ * @param {string} s
+ * @param {string} t
+ * @return {boolean}
+ * https://leetcode.com/problems/valid-anagram/
+ */
+var isAnagram = function(s, t) {
+    if (s.length !== t.length) {
+        return false;
+    }
+    let sArr = s.split('');
+    let tArr = t.split('');
+    let map = {};
+    
+    for (let i = 0; i < sArr.length; i++) {
+        if (!map[sArr[i]]) {
+            map[sArr[i]] = 1;
+        } else {
+            map[sArr[i]]++;
+        }
+    }
+    
+    for (let i = 0; i < tArr.length; i++) {
+        if (!map[tArr[i]] || map[tArr[i]] <= 0) {
+            return false;
+        }
+        map[tArr[i]]--;
+    }
+    return true;
+};
\ No newline at end of file
diff --git a/Week_02/id_39/LeetCode_3_39.js b/Week_02/id_39/LeetCode_3_39.js
new file mode 100644
index 00000000..b662e914
--- /dev/null
+++ b/Week_02/id_39/LeetCode_3_39.js
@@ -0,0 +1,20 @@
+/**
+ * @param {string} s
+ * @return {number}
+ * https://leetcode.com/problems/longest-substring-without-repeating-characters/
+ */
+var lengthOfLongestSubstring = function(s) {
+    let sArr = s.split('');
+    let max = 0;
+    let map = {};
+    let left = 0;
+    for (let i = 0; i < sArr.length; i++) {
+        if (map[sArr[i]] != null) {
+            left = Math.max(left, map[sArr[i]] + 1);
+        }
+        map[sArr[i]] = i;
+        max = Math.max(max, i - left + 1);
+    }
+        
+    return max;
+};
\ No newline at end of file