Merge pull request #15 from Ankur-Dwivedi22/day_1easy

chore: completed day1 easy task

easy/day_1/.cph/.solution.cpp_ad0d3167fa989b5dc9570fc4375b146a.prob

@@ -0,0 +1 @@
+{"name":"Local: solution","url":"d:\\OPCODE\\Code\\codecrack\\easy\\day_1\\solution.cpp","tests":[{"id":1711178288869,"input":"4\n7\n1 1 1 1 1 1 1\n4\n3 2 1 3\n3\n1 2 3\n1\n1","output":"35 \n2\n0\n0"}],"interactive":false,"memoryLimit":1024,"timeLimit":3000,"srcPath":"d:\\OPCODE\\Code\\codecrack\\easy\\day_1\\solution.cpp","group":"local","local":true}

easy/day_1/solution.cpp

@@ -3,34 +3,56 @@
 using namespace std;
 int main()
 {
-    int t;
-    cin >> t;
-    while (t--)
+    int test;
+    cin >> test;
+    while (test--)
     {
-        lil n;
-        cin >> n;
-        lil a[n];
-        for (int i = 0; i < n; i++)
-            cin >> a[i];
-        sort(a, a + n);
-        lil c = 1, s = 0;
-        for (int i = 1; i < n; i++)
+        lil num; //number of sticks
+        cin >> num;
+
+        //creating vector vector instead of array as it is logically incorrect to take input from user and then assign the size of array to that input
+        vector<lil> length_of_sticks(num); 
+        //stores length of each stick
+
+        for (int i = 0; i < num; i++)
+            cin >> length_of_sticks[i];
+        //sorting the vector for searching triplets of triangle in vector in single loop
+        sort(length_of_sticks.begin() , length_of_sticks.end());
+
+        lil count = 1, ans = 0;
+        //count -> keeps track of same length sticks
+        //ans-> keeps track of total number of triplets
+        //1LL is multiplied to avoid any kind of multiplication overflow
+        for (int i = 1; i < num; i++)
         {
-            if (a[i] == a[i - 1])
-                c++;
+            //if the current length of stick is equal to previous one it increments count by one
+            if (length_of_sticks[i] == length_of_sticks[i - 1]) 
+                count++;
+
+            //if above condition does not holds then it implies count of identical length sticks encountered so far = count
             else
             {
-                if (c >= 3)
-                    s += c * (c - 1) * (c - 2) / 6;
-                if (i - c > 0)
-                    s += c * (c - 1) / 2 * (i - c);
-                c = 1;
+                //calculating number of triplets within group of count
+                //count >= 3 then nC3 = n*(n-1)*(n-2)/6
+                //add the result to final answer
+                if (count >= 3)
+                    ans += count *1LL* (count - 1) *1LL* (count - 2) / 6;
+
+                //selecting two elements from group of identical length sticks : nC2 = n*(n-1)/2
+                //rest other element = (i-count)
+                //add the result to final answer
+                if (i - count > 0)
+                    ans += count *1LL* (count - 1) / 2 *1LL* (i - count);
+                count = 1;
             }
         }
-        if (c >= 3)
-            s += c * (c - 1) * (c - 2) / 6;
-        if (n - c > 0)
-            s += c * (c - 1) / 2 * (n - c);
-        Cout << s << endl;
+
+        //after processing all the sticks if there are remaining identical sticks >= 3 then follow the same approach nC3
+        if (count >= 3)
+            ans += count *1LL* (count - 1) *1LL* (count - 2) / 6;
+        //same approach of selecting two elements from identical and rest others
+        if (num - count > 0)
+            ans += count *1LL* (count - 1) / 2 *1LL* (num - count);
+        cout << ans << endl; //Cout is changed to cout
     }
 }