added a program in arrays

Author: smv1999

Arrays/duplicates_in_array.cpp

@@ -0,0 +1,43 @@
+#include <bits/stdc++.h>
+using namespace std;
+vector<int> duplicates(int arr[], int n);
+int main()
+{
+    int t;
+    cin >> t;
+    while (t-- > 0)
+    {
+        int n;
+        cin >> n;
+        int a[n];
+        for (int i = 0; i < n; i++)
+            cin >> a[i];
+        vector<int> ans = duplicates(a, n);
+        for (int i : ans)
+            cout << i << ' ';
+        cout << endl;
+    }
+    return 0;
+}
+
+vector<int> duplicates(int a[], int n)
+{
+    map<int, int> mp;
+    vector<int> res;
+    int index, flag = 0;
+    for (index = 0; index < n; index++)
+        mp[a[index]]++;
+    for (auto i : mp)
+    {
+        if (i.second > 1)
+        {
+            res.push_back(i.first);
+            flag = 1;
+        }
+    }
+    if (!flag)
+    {
+        res.push_back(-1);
+    }
+    return res;
+}