diff --git a/contains-duplicate/krokerdile.js b/contains-duplicate/krokerdile.js
new file mode 100644
index 000000000..17c709498
--- /dev/null
+++ b/contains-duplicate/krokerdile.js
@@ -0,0 +1,48 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+
+/**
+ * 1차 풀이
+ * - Map을 사용하여 각 숫자의 개수를 세는 방법
+ */
+var containsDuplicate = function(nums) {
+    let dict = new Map();
+
+    nums.forEach((num)=>{
+        if(dict.has(num)){
+            dict.set(num, dict.get(num)+1);
+        }else{
+            dict.set(num, 1);
+        }
+    })
+
+    for (const num of nums) {
+        if(dict.get(num) >= 2){
+            return true;
+        }
+    }
+    return false;
+};
+
+/**
+ * 2차풀이
+ * - Map을 사용하여 각 숫자의 개수를 세는 방법
+ * - forEach를 사용하지 않고 for of문을 사용하여 반복문을 돌리는 방법 
+ */
+var containsDuplicate = function(nums) {
+    let dict = new Map();
+
+    for (const num of nums) {
+         if(dict.has(num)){
+            dict.set(num, dict.get(num)+1);
+        }else{
+            dict.set(num, 1);
+        }
+        if(dict.get(num) >= 2){
+            return true;
+        }
+    }
+    return false;
+};
diff --git a/house-robber/krokerdile.js b/house-robber/krokerdile.js
new file mode 100644
index 000000000..7ab2d2fa4
--- /dev/null
+++ b/house-robber/krokerdile.js
@@ -0,0 +1,18 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var rob = function(nums) {
+    if (nums.length === 0) return 0;
+    if (nums.length === 1) return nums[0];
+
+    let dp = new Array(nums.length);
+    dp[0] = nums[0];
+    dp[1] = Math.max(nums[0], nums[1]);
+
+    for (let i = 2; i < nums.length; i++) {
+        dp[i] = Math.max(dp[i - 1], nums[i] + dp[i - 2]);
+    }
+
+    return dp[nums.length - 1];
+};
diff --git a/longest-consecutive-sequence/krokerdile.js b/longest-consecutive-sequence/krokerdile.js
new file mode 100644
index 000000000..bd53b8db6
--- /dev/null
+++ b/longest-consecutive-sequence/krokerdile.js
@@ -0,0 +1,28 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var longestConsecutive = function(nums) {
+    if (nums.length === 0) return 0;
+
+    const numSet = new Set(nums);
+    let maxLength = 0;
+
+    for (let num of numSet) {
+        // 연속 수열의 시작점인지 확인
+        if (!numSet.has(num - 1)) {
+            let currentNum = num;
+            let currentLength = 1;
+
+            // 연속된 숫자 있는 동안 증가
+            while (numSet.has(currentNum + 1)) {
+                currentNum += 1;
+                currentLength += 1;
+            }
+
+            maxLength = Math.max(maxLength, currentLength);
+        }
+    }
+
+    return maxLength;
+};
diff --git a/top-k-frequent-elements/krokerdile.js b/top-k-frequent-elements/krokerdile.js
new file mode 100644
index 000000000..979e92d1f
--- /dev/null
+++ b/top-k-frequent-elements/krokerdile.js
@@ -0,0 +1,26 @@
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number[]}
+ */
+var topKFrequent = function(nums, k) {
+    let dict = new Map();
+    let temp = Array.from(new Set([...nums]));
+    for(const num of nums){
+        if(dict.has(num)){
+            dict.set(num, dict.get(num)+1);
+        }else{
+            dict.set(num,1);
+        }
+    }
+
+    temp = temp.sort((a,b)=>{
+        let aCount = dict.get(a);
+        let bCount = dict.get(b);
+
+        return bCount - aCount;
+    })
+
+    let slice = temp.slice(0,k);
+    return slice;
+};
diff --git a/two-sum/krokerdile.js b/two-sum/krokerdile.js
new file mode 100644
index 000000000..ce0664586
--- /dev/null
+++ b/two-sum/krokerdile.js
@@ -0,0 +1,15 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[]}
+ */
+var twoSum = function(nums, target) {
+    let dict = new Map();
+
+    for(const [index, num] of nums.entries()){
+        if(dict.has(target-num) && dict.get(target-num) != index){
+            return [dict.get(target-num),index];
+        }
+        dict.set(num, index);
+    }
+};