Add contains-duplicate solution using Set in TypeScript

Author: Jeehay28

contains-duplicate/Jeehay28.ts

@@ -0,0 +1,60 @@
+// Approach 3: HashSet (Using TypeScript Set)
+// ⏳ Time Complexity: O(n)
+// 💾 Space Complexity: O(n)
+
+function containsDuplicate(nums: number[]): boolean {
+
+    const seen = new Set<number>();
+
+    for (const num of nums) {
+        if (seen.has(num)) {
+            return true;
+        }
+        seen.add(num);
+    }
+
+    return false;
+
+};
+
+
+// Approach 2: Sorting + Scan
+// ⏳ Time Complexity: O(n * log(n)) ❌ (Faster than O(n^2), but still not optimal)
+// 💾 Space Complexity: O(1)
+
+// function containsDuplicate(nums: number[]): boolean {
+
+//     nums.sort();
+
+//     for (let i = 0; i < nums.length - 1; i++) {
+//         if (nums[i] === nums[i + 1]) {
+//             return true;
+//         }
+//     }
+
+//     return false;
+
+// };
+
+
+// Approach 1: Brute Force (O(n^2))
+// 🚨⏳ TLE (Time Limit Exceeded)!
+// ⏳ Time Complexity: O(n^2) ❌ (Inefficient for large inputs)
+// 💾 Space Complexity: O(1) ✅ (Great, no extra memory used!)
+
+// function containsDuplicate(nums: number[]): boolean {
+
+//     for (let i = 0; i < nums.length; i++) {
+//         for (let j = i + 1; j < nums.length; j++) {
+//             if (nums[i] === nums[j]) {
+//                 return true;
+//             }
+//         }
+//     }
+
+//     return false;
+
+// };
+
+
+