diff --git a/best-time-to-buy-and-sell-stock/uraflower.js b/best-time-to-buy-and-sell-stock/uraflower.js
new file mode 100644
index 000000000..8012dfe8b
--- /dev/null
+++ b/best-time-to-buy-and-sell-stock/uraflower.js
@@ -0,0 +1,18 @@
+/**
+ * 주어진 prices에서 가장 큰 prices[j] - prices[i] (i < j) 를 반환하는 함수
+ * @param {number[]} prices
+ * @return {number}
+ */
+const maxProfit = function(prices) {
+    let min = prices[0];
+    let profit = 0;
+    
+    for (const price of prices) {
+        min = Math.min(min, price);
+        profit = Math.max(profit, price - min);
+    }
+
+    return profit;
+};
+// 시간복잡도: O(n)
+// 공간복잡도: O(1)
diff --git a/encode-and-decode-strings/uraflower.js b/encode-and-decode-strings/uraflower.js
new file mode 100644
index 000000000..c1e16d8ef
--- /dev/null
+++ b/encode-and-decode-strings/uraflower.js
@@ -0,0 +1,16 @@
+const encode = function (strs) {
+  const separator = '\\';
+  return strs.join(separator);
+}
+
+
+const decode = function (str) {
+  const separator = '\\';
+  return str.split(separator);
+}
+
+// 문제가 너무 별로다
+// 문제에서 제시하고 있는 해답도 별로다
+// 이모지같은 걸 구분자로 쓰거나, length를 앞에 넣어서 구별하거나 해도 사실 제대로 암호화했다고 말할 수 없음
+// 그런 걸 정답으로 제공할 거면 이런 문제를 왜 내는 거여
+// 이 문제가 Blind 75에 속해 있는 이유가 뭘까...?!
diff --git a/group-anagrams/uraflower.js b/group-anagrams/uraflower.js
new file mode 100644
index 000000000..c014f7398
--- /dev/null
+++ b/group-anagrams/uraflower.js
@@ -0,0 +1,32 @@
+/**
+ * 애너그램끼리 묶어서 반환하는 함수
+ * @param {string[]} strs
+ * @return {string[][]}
+ */
+const groupAnagrams = function(strs) {
+  // 풀이 1
+  // 시간복잡도: O(n*s) (n: strs.length, s: str.length)
+  // 공간복잡도: O(n)
+  function groupManually () {
+    const groups = {};
+
+    strs.forEach((str) => {
+        const key = [...str].sort().join('');
+        if (!groups[key]) groups[key] = [];
+        groups[key].push(str);
+    });
+
+    return  Object.values(groups);
+  }
+
+  // 풀이 2
+  // 시간복잡도: O(n*s) (n: strs.length, s: str.length)
+  // 공간복잡도: O(n)
+  function groupByAnagram() {
+    const result = Object.groupBy(strs, (str) => [...str].sort().join(''));
+    return  Object.values(result);
+  }
+
+  return groupByAnagram();
+};
+
diff --git a/implement-trie-prefix-tree/uraflower.js b/implement-trie-prefix-tree/uraflower.js
new file mode 100644
index 000000000..e342e6d08
--- /dev/null
+++ b/implement-trie-prefix-tree/uraflower.js
@@ -0,0 +1,65 @@
+const Node = function (value) {
+    this.value = value;
+    this.children = {};
+    this.data = null;
+}
+
+const Trie = function () {
+    this.root = new Node(null);
+};
+
+/** 
+ * @param {string} word
+ * @return {void}
+ */
+Trie.prototype.insert = function (word) {
+    let parent = this.root;
+
+    for (let i = 0; i < word.length; i++) {
+        if (!parent.children[word[i]]) {
+            parent.children[word[i]] = new Node(word[i]);
+        }
+        parent = parent.children[word[i]];
+    }
+
+    parent.data = word;
+};
+
+/** 
+ * @param {string} word
+ * @return {boolean}
+ */
+Trie.prototype.search = function (word) {
+    let parent = this.root;
+    let i = 0;
+
+    while (i < word.length && parent.children[word[i]]) {
+        parent = parent.children[word[i]];
+        i += 1;
+    }
+
+    return parent.data === word;
+};
+
+/** 
+ * @param {string} prefix
+ * @return {boolean}
+ */
+Trie.prototype.startsWith = function (prefix) {
+    let parent = this.root;
+
+    for (let char of prefix) {
+        if (!parent.children[char]) return false;
+        parent = parent.children[char];
+    }
+
+    return true;
+};
+
+/** 
+ * Your Trie object will be instantiated and called as such:
+ * var obj = new Trie()
+ * obj.insert(word)
+ * var param_2 = obj.search(word)
+ * var param_3 = obj.startsWith(prefix)
+ */
diff --git a/word-break/uraflower.js b/word-break/uraflower.js
new file mode 100644
index 000000000..4cbeb36e9
--- /dev/null
+++ b/word-break/uraflower.js
@@ -0,0 +1,30 @@
+/**
+ * @param {string} s
+ * @param {string[]} wordDict
+ * @return {boolean}
+ */
+const wordBreak = function (s, wordDict) {
+    const dp = Array(s.length);
+    const dict = new Set(wordDict);
+
+    function recurse(start) {
+        if (start === s.length) return true;
+        if (dp[start] !== undefined) return dp[start];
+
+        for (let end = start + 1; end <= s.length; end++) {
+            const substr = s.slice(start, end);
+            if (dict.has(substr) && recurse(end)) {
+                dp[start] = true;
+                return true;
+            }
+        }
+
+        dp[start] = false;
+        return false;
+    }
+
+    return recurse(0);
+};
+
+// 시간복잡도: O(n^2) (n: s.length. n번 재귀 & 최대 n번 슬라이싱)
+// 공간복잡도: O(n + m) (m: wordDict.length)