Restructured the example folder and added new examples

examples/hashset/README.md

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+# Hashset examples
+
+* set_ops.c - Demonstrates common set operations like *union*, *intersection*, *difference* and *symmetric difference*.

examples/hashset/set_ops.c

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+/**
+ * set_ops.c
+ *
+ * Creation Date: 03/04/2019
+ *
+ * Authors:
+ * Leonardo Vencovsky (https://github.com/LeoVen)
+ *
+ */
+
+// Demonstration of set operations like:
+// - Union
+// - Intersection
+// - Difference
+// - Symmetric Difference
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "hashset.h"
+
+// change to hashset to have the same effects
+HASHSET_GENERATE(set, set, /* static */, int)
+
+void print_set(set *s)
+{
+    size_t index;
+    int result;
+    set_iter iter;
+    set_iter_new(&iter, s);
+    for (set_iter_tostart(&iter); !set_iter_end(&iter);)
+    {
+        set_iter_next(&iter, &result, &index);
+        if (index == 0)
+            printf("[ %2d, ", result);
+        else if (index == s->count - 1)
+            printf("%2d ]\n", result);
+        else
+            printf("%2d, ", result);
+    }
+}
+
+int intcmp(int a, int b)
+{
+    return a - b;
+}
+
+size_t inthash(int t)
+{
+    size_t a = t;
+    a += ~(a << 15);
+    a ^= (a >> 10);
+    a += (a << 3);
+    a ^= (a >> 6);
+    a += ~(a << 11);
+    a ^= (a >> 16);
+    return a;
+}
+
+int main(int argc, char const *argv[])
+{
+    set *set1 = set_new(50, 0.9, intcmp, inthash);
+    set *set2 = set_new(50, 0.9, intcmp, inthash);
+
+    for (int i = 1; i <= 20; i++)
+        set_insert(set1, i);
+
+    for (int i = 11; i <= 30; i++)
+        set_insert(set2, i);
+
+    set *set3 = set_union(set1, set2);
+
+    print_set(set1);
+    printf("UNION\n");
+    print_set(set2);
+    printf("=\n");
+    print_set(set3);
+
+    printf("\n\n");
+
+    set *set4 = set_intersection(set1, set2);
+
+    print_set(set1);
+    printf("INTERSECTION\n");
+    print_set(set2);
+    printf("=\n");
+    print_set(set4);
+
+    printf("\n\n");
+
+    set *set5 = set_difference(set1, set2);
+
+    print_set(set1);
+    printf("DIFFERENCE\n");
+    print_set(set2);
+    printf("=\n");
+    print_set(set5);
+
+    printf("\n\n");
+
+    set *set6 = set_symmetric_difference(set1, set2);
+
+    print_set(set1);
+    printf("SYMMETRIC DIFFERENCE\n");
+    print_set(set2);
+    printf("=\n");
+    print_set(set6);
+
+    set_free(set1);
+    set_free(set2);
+    set_free(set3);
+    set_free(set4);
+    set_free(set5);
+    set_free(set6);
+
+    return 0;
+}