start c++ implementation

cpp_src/Makefile

@@ -0,0 +1,17 @@
+CSW = -O3 -Wall
+LSW = -lfd
+
+all:
+	make collatz
+
+collatz: collatz.o Makefile
+	g++ collatz.o -o collatz
+
+collatz.o: collatz.cc Makefile
+	g++ collatz.cc -c -o collatz.o $(CSW)
+
+collatz.cc: collatz.h Makefile
+	touch collatz.cc
+
+clean:
+	touch Makefile; make

cpp_src/collatz.cc

@@ -1,12 +1,38 @@
+// Ben Harris
+
 #import <unistd.h>
+#import <cstdlib>
+#import <string>
+#import <iostream>
+#import "collatz.h"
+using namespace std;
 
+int *prev = new int[1000000];
+int maxcnt = 0, maxsteps = 0;
 
+int main (int argc, char **argv) {
+  cout << "cCollatz" << endl;
+  for (int i = 1; i <= 100000; i++) {
+    cout << i << "\tnum of steps: " << collatz(i) << endl;
+  }
+  cout << "Longest path was " << maxsteps << " steps for " << maxcnt << endl;
+}
 
 int collatz (int start) {
   int cnt = 0;
+  int initval = start;
   while(start != 1) {
     cnt++;
+    if (start < 1000000 && prev[start] != 0) {
+      start = prev[start];
+      continue;
+    }
     start = start % 2 == 0 ? start/2 : 3*start + 1;
   }
+  prev[start] = cnt;
+  if (cnt > maxcnt) {
+    maxcnt = initval;
+    maxsteps = cnt;
+  }
   return cnt;
 }

cpp_src/collatz.h

@@ -0,0 +1,10 @@
+// Ben Harris
+
+#ifndef _COLLATZ_h_
+#define _COLLATZ_h_
+
+// method definitions
+int main(int argc, char **argv);
+int collatz(int start);
+
+#endif

java_src/Collatz.java

@@ -1,3 +1,5 @@
+// Ben Harris
+
 class Collatz {
 
   int prev[] = new int[1000000];
@@ -5,7 +7,7 @@ class Collatz {
   int maxsteps = 0;
 
   public static void main(String[] args) {
-    System.out.println("collatz calc");
+    System.out.println("javaCollatz");
 
     Collatz c = new Collatz();