Working benchmarks

Makefile

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+
+DIRS=c++ ruby python perl php
+
+bench: 
+	@for dir in $(DIRS); do \
+		echo $$dir ; \
+		$(MAKE) --no-print-directory -C $$dir bench; \
+	done

README

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+Array Intersection Bake-off
+
+One of those moments where an interview question turns into a research
+project, or is it really a bake off?  The simple problem is demonstrate
+an algorithm to intersect two lists of numbers, fundamentally it's
+question about using modern interpreted languages and their associative
+array bits to make a simple intersection routine.  However many languages
+support many different ways to do things.  I've put together a test
+of Python vs. Java vs. Ruby vs. Perl vs. PHP and got a few interesting
+benchmarks.
+

c++/Makefile

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+
+bench: isect_1_cxx
+	@echo -n 'isect_1_cxx | '
+	@./isect_1_cxx ../data.txt
+
+isect_1_cxx : isect_1_cxx.cxx
+	$(CXX) -g -o $@ isect_1_cxx.cxx
+

c++/isect_1_cxx.cxx

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+#include <stdio.h>
+#include <unistd.h>
+#include <strings.h>
+#include <backward/hash_set>
+#include <list>
+#include <time.h>
+
+std::list<int>* isect(int len, int a[], int b[]) {
+    __gnu_cxx::hash_set<int>   h = __gnu_cxx::hash_set<int>();
+
+    for (int i = 0; i < len; i++) 
+        h.insert(a[i]);
+
+    std::list<int>   *l = new std::list<int>();
+
+    for (int i = 0; i < len; i++) 
+        if (h.find(b[i]) != h.end()) 
+            l->push_back(b[i]);
+
+    return l;
+}
+
+main(int argc, char *argv[]) {
+    FILE    *fd;
+    char    buf[1024];
+    int     size;
+
+    if (argc == 1) 
+        fd = stdin;
+    else
+        fd = fopen(argv[1], "r");
+
+    fgets(buf, sizeof(buf), fd);
+    size = atoi(buf);
+
+    int     *x = new int[size];
+    int     *y = new int[size];
+    int     idx = 0;
+
+    while (fgets(buf, sizeof(buf), fd) != NULL) {
+        const char    *cp = index(buf, ' ');
+
+        x[idx] = atoi(buf); 
+        y[idx] = atoi(cp+1); 
+        idx++;
+    }
+
+    clock_t         t0 = clock();
+    std::list<int>  *l = isect(idx, x, y);
+    clock_t         t1 = clock();
+
+    printf("Set   | n = %d : %d intersects found in %f seconds\n", idx, l->size(), (double)(t1 - t0) / CLOCKS_PER_SEC);
+
+    fclose(fd);
+}