Suffix tree implementation file i added

Suffix tree/suffix _tree_impl.cpp

@@ -0,0 +1,40 @@
+#include <sdsl/suffix_trees.hpp>
+#include <iostream>
+
+using namespace std;
+using namespace sdsl;
+
+typedef cst_sct3<> cst_t;
+typedef cst_t::char_type char_type;
+
+int main(int argc, char* argv[])
+{
+    if (argc < 2) {
+        cout << "Usage: "<< argv[0] << " file" << endl;
+        cout << "(1) Generates the CST of file." << endl;
+        cout << "(2) Calculates the avg LCP value and the runs in the BWT." << endl;
+        return 1;
+    }
+    cst_t cst;
+    construct(cst, argv[1], 1);
+
+    long double runs = 1;
+    long double avg_lcp = 0;
+    if (cst.csa.size()) {
+        char_type prev_bwt = cst.csa.bwt[0];
+        for (uint64_t i=1; i<cst.csa.size(); ++i) {
+            char_type bwt = cst.csa.bwt[i];
+            if (prev_bwt != bwt) {
+                runs += 1.0;
+            }
+            prev_bwt = bwt;
+            avg_lcp += cst.lcp[i];
+        }
+        avg_lcp /= cst.csa.size();
+        for (size_t k=0; k<=5; k++) {
+            cout << "H_" << k << ": " << Hk(cst,k).first << endl;
+        }
+        cout << "avg LCP: " << avg_lcp << endl;
+        cout << "runs in BWT: " << runs << endl;
+    }
+}