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More comments added to the code

Co-authored-by: David Leal <[email protected]>

strings/z_function.cpp

@@ -11,14 +11,14 @@
  * @author [Ritika Gupta](https://github.com/RitikaGupta8734)
  */
 
-#include <iostream>
+#include <iostream> /// for IO operations
 #ifdef _MSC_VER
-#include <string> // use this for MS Visual C++
+#include <string> /// for string (use this for MS Visual C++)
 #else
-#include <cstring>
+#include <cstring> /// for string
 #endif
-#include <vector>
-# include <cassert>
+#include <vector> /// for std::vector
+#include <cassert> /// for assert
 
 /**
  * Generate the Z-function for the inputted string.