Adding a tutorial for dimik-factorial (#476)

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Author: nfpranta

dimik-factorial/en.md

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+# Dimik - Factorial
+
+In this problem, you will be given `T` testcases. Each line of the testcase consists of an integer `n`. We have to determine the factorial value of `n`
+
+### Solution
+Factorial of any value n denotes finding the product of all the values starting from 1 upto n.
+In other words, `Factorial[n]=1*2*3*4...*(n-2)*(n-1)*n`.
+So we can make an efficient solution, by preprocessing all the factorials for different possible values of n and while going through the test cases,we can just print out the factorial of `n`.
+
+### C++
+```cpp
+#include <bits/stdc++.h>
+using namespace std;
+int main()
+{
+    int fact[16];
+    fact[0] = 1;
+    for (int i = 1; i <= 15; i++)
+    {
+        fact[i] = i * fact[i - 1];
+    }
+    int t;
+    cin >> t;
+    while (t--)
+    {
+        int n;
+        cin >> n;
+        cout << fact[n] << endl;
+    }
+}
+```