diff --git a/contains-duplicate/hozzijeong.js b/contains-duplicate/hozzijeong.js
new file mode 100644
index 0000000000..47da62bf1d
--- /dev/null
+++ b/contains-duplicate/hozzijeong.js
@@ -0,0 +1,10 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var containsDuplicate = function(nums) {
+    const originLength = nums.length;
+    const numsSet = new Set(nums);
+
+    return originLength !== numsSet.size;
+};
diff --git a/longest-consecutive-sequence/hozzijeong.js b/longest-consecutive-sequence/hozzijeong.js
new file mode 100644
index 0000000000..9f7c468a62
--- /dev/null
+++ b/longest-consecutive-sequence/hozzijeong.js
@@ -0,0 +1,33 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var longestConsecutive = function(nums) {
+    const numsSet = new Set(nums);
+
+
+    if(nums.length === 0) return 0
+
+    const sortedNums = [...numsSet].sort((a,b) => a-b);
+
+    const results = [];
+
+    let result = 1;
+
+    for(let i = 0; i < sortedNums.length-1; i++){
+        const current = sortedNums[i];
+        const next = sortedNums[i+1];
+
+        if((current + 1) === next){
+            result += 1;
+        }else{
+            results.push(result);
+            result = 1;
+        }
+    }
+
+    results.push(result);
+
+
+    return Math.max(...results)
+};
diff --git a/top-k-frequent-elements/hozzijeong.js b/top-k-frequent-elements/hozzijeong.js
new file mode 100644
index 0000000000..cd1e51866d
--- /dev/null
+++ b/top-k-frequent-elements/hozzijeong.js
@@ -0,0 +1,25 @@
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number[]}
+ */
+var topKFrequent = function(nums, k) {
+    const numsMap = new Map();
+
+    for(const num of nums){
+        const currentNums = numsMap.get(num);
+
+        if(!currentNums){
+            numsMap.set(num, 1);
+            continue;
+        }
+
+        numsMap.set(num, currentNums + 1)
+    }
+
+    const sortedNums = [...numsMap].sort((a,b) => b[1] - a[1]);
+
+    const frequencyNums = sortedNums.map(([num])=> num);
+
+    return frequencyNums.slice(0,k);
+};
diff --git a/two-sum/hozzijeong.js b/two-sum/hozzijeong.js
new file mode 100644
index 0000000000..5b9178e07e
--- /dev/null
+++ b/two-sum/hozzijeong.js
@@ -0,0 +1,17 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[]}
+ */
+var twoSum = function(nums, target) {
+    for(let i =0; i < nums.length - 1; i++){
+        const first = nums[i];
+        for(let j = i + 1; j < nums.length; j++){
+            const last = nums[j];
+
+            if((first + last) === target) return [i,j]
+        }
+    }
+
+    return []
+};