Merge pull request #2391 from u-siop/main

[u-siop] WEEK 01 solutions

Author: SamTheKorean

contains-duplicate/u-siop.cpp

@@ -0,0 +1,20 @@
+class Solution {
+public:
+    bool containsDuplicate(vector<int>& nums) {
+        // instinct : sort the array and check all the array whether duplicate or not
+        // time complexity : NlogN(sort) + N(check all the array)
+        // space complexity : 1
+
+        // how do we, in real world, judge there is a duplicated element, definitely need a reference( another data strucrue) to check
+
+        unordered_map<int, bool> seen; // using hash map for updating, already have seen the element
+
+        for (const auto& i : nums) {
+            if (seen[i] >= 1)
+                return true;
+            seen[i] = true;
+        }
+
+        return false;
+    }
+};