diff --git a/contains-duplicate/robinyoon-dev.js b/contains-duplicate/robinyoon-dev.js
new file mode 100644
index 0000000000..ab6044ea70
--- /dev/null
+++ b/contains-duplicate/robinyoon-dev.js
@@ -0,0 +1,17 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var containsDuplicate = function(nums) {
+  let arrToSet = new Set(nums);
+  
+  const originalLength = nums.length;
+  const filteredLength = arrToSet.size;
+
+  if(originalLength === filteredLength){
+    return false; // 겹치는 숫자가 없는 경우
+  } else {
+    return true; // 겹치는 숫자가 있는 경우
+  }
+
+};
diff --git a/house-robber/robinyoon-dev.js b/house-robber/robinyoon-dev.js
new file mode 100644
index 0000000000..a39e60d1ad
--- /dev/null
+++ b/house-robber/robinyoon-dev.js
@@ -0,0 +1,22 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var rob = function (nums) {
+
+    const NUMS_LENGTH = nums.length;
+
+    if (NUMS_LENGTH === 0) return 0;
+    if (NUMS_LENGTH === 1) return nums[0];
+
+    const maxSumsArr = new Array(NUMS_LENGTH);
+    maxSumsArr[0] = nums[0];
+    maxSumsArr[1] = Math.max(nums[0], nums[1]);
+
+    for (let i = 2; i < NUMS_LENGTH; i++) {
+        maxSumsArr[i] = Math.max(maxSumsArr[i - 2] + nums[i], maxSumsArr[i - 1]);
+    }
+
+    return maxSumsArr[NUMS_LENGTH - 1];
+
+};
diff --git a/longest-consecutive-sequence/robinyoon-dev.js b/longest-consecutive-sequence/robinyoon-dev.js
new file mode 100644
index 0000000000..6055417f9b
--- /dev/null
+++ b/longest-consecutive-sequence/robinyoon-dev.js
@@ -0,0 +1,38 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var longestConsecutive = function (nums) {
+
+    //엣지케이스: 빈배열인 경우
+    if (nums.length === 0) {
+        return 0;
+    }
+
+    //Set으로 중복값 제거하기
+    const numsSet = new Set(nums);
+
+    let tempMaxLength = 1;
+
+    for (num of numsSet) {
+        let startPoint = num - 1;
+        let hasStart = numsSet.has(startPoint);
+
+        //!hasStart인 num이 첫번째에 와야할 수니까!
+        if (!hasStart) {
+
+            let currentLength = 1;
+
+            while (numsSet.has(num + currentLength)) {
+                currentLength++;
+            }
+            // max 찾기
+            tempMaxLength = Math.max(currentLength, tempMaxLength);
+        } else {
+            continue;
+        }
+    }
+
+    return tempMaxLength;
+
+};
diff --git a/top-k-frequent-elements/robinyoon-dev.js b/top-k-frequent-elements/robinyoon-dev.js
new file mode 100644
index 0000000000..429bea1452
--- /dev/null
+++ b/top-k-frequent-elements/robinyoon-dev.js
@@ -0,0 +1,33 @@
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number[]}
+ */
+var topKFrequent = function(nums, k) {
+    let numsMap = new Map();
+
+    for (let i = 0; i < nums.length; i++) {
+        // 1.  numsMap에 nums[i]가 key로 있나 확인
+        // 1-1. 있으면 nums[i]와 동일한 key를 찾은 후 value에 +1
+        // 1-2. 없으면 새로 생성 & value를 1로.
+        let hasNum = numsMap.has(nums[i]);
+        if (hasNum) {
+            numsMap.set(nums[i], numsMap.get(nums[i]) + 1);
+        } else {
+            numsMap.set(nums[i], 1);
+        }
+    }
+
+    // 2. numsMap을 배열로 변경 (mapToArr)
+    // 3. mapToArr에서 value가 가장 놓은 순대로 sort
+    // 4. mapToArr를 k개 까지만 잘라낸 후 
+    // 5. mapToArr의 각 아이템의 0번째 값만 추출하여 새로운 배열 만들고 return
+    let mapToArr = Array.from(numsMap);
+
+    mapToArr.sort((a, b) => b[1] - a[1]);
+
+    const slicedMapToArr = mapToArr.slice(0, k);
+    const result = slicedMapToArr.map((item) => item[0]);
+
+    return result;
+};
diff --git a/two-sum/robinyoon-dev.js b/two-sum/robinyoon-dev.js
new file mode 100644
index 0000000000..a528c1d951
--- /dev/null
+++ b/two-sum/robinyoon-dev.js
@@ -0,0 +1,21 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[]}
+ */
+var twoSum = function (nums, target) {
+    for (let i = 0; i < nums.length; i++) {
+        let remaindedNum = target - nums[i];
+        let matchedNum = nums.find((item) => remaindedNum === item);
+        let matchedNumIndex = nums.indexOf(matchedNum, i + 1);
+        // i와 matchedNumIndex 이 같은 숫자면 안 됨.
+        if (i === matchedNumIndex) {
+            continue;
+        } else if (matchedNumIndex === -1) {
+            continue;
+        }
+        else {
+            return [i, matchedNumIndex];
+        }
+    }
+};