9 files changed, 282 insertions, 0 deletions

diff --git a/usth/ICT2.1/labwork/3/Ex1.c b/usth/ICT2.1/labwork/3/Ex1.c
new file mode 100644
index 0000000..90b3ca5
--- /dev/null
+++ b/usth/ICT2.1/labwork/3/Ex1.c
@@ -0,0 +1,38 @@
+/*
+ * Reverse name from stdin.
+ * This is free and unencumbered software released into the public domain.
+ */
+
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "stack.h"
+
+int main()
+{
+	stack *s = mkstack();
+	char c, *p;
+
+	while ((c = getchar()) != EOF) {
+		p = malloc(sizeof(char *));
+		*p = isspace(c) ? 32 : c;
+		stack_push(s, p);
+	}
+
+	while (!stack_empty(s) && *(char *) stack_top(s) == 32) {
+		p = stack_pop(s);
+		free(p);
+	}
+
+	c = 32;
+	while (!stack_empty(s)) {
+		p = stack_pop(s);
+		putchar(c == 32 ? toupper(c = *p) : tolower(c = *p));
+		free(p);
+	}
+
+	putchar(10);
+
+	return 0;
+}
diff --git a/usth/ICT2.1/labwork/3/Ex2.c b/usth/ICT2.1/labwork/3/Ex2.c
new file mode 100644
index 0000000..49be21b
--- /dev/null
+++ b/usth/ICT2.1/labwork/3/Ex2.c
@@ -0,0 +1,61 @@
+/*
+ * Add hard-coded names to a queue a print them to stdout.
+ * This is free and unencumbered software released into the public domain.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "construct.h"
+
+typedef struct {
+	construct *front;
+	construct *rear;
+} queue;
+
+queue *mkq()
+{
+	queue *q = malloc(sizeof(queue));
+	q->front = q->rear = NULL;
+}
+
+int qempty(queue *q)
+{
+	return q->front == NULL;
+}
+
+void qpush(queue *q, void *item)
+{
+	if (qempty(q))
+		q->front = q->rear = cons(item, NULL);
+	else
+		q->rear = q->rear->cdr = cons(item, NULL);
+}
+
+void *qpop(queue *q)
+{
+	if (qempty(q))
+		return NULL;
+	void *first = car(q->front);
+	construct *rest = cdr(q->front);
+	free(q->front);
+	q->front = rest;
+	return first;
+}
+
+int main()
+{
+	queue *q = mkq();	
+	qpush(q, "Mahathir Mohamad");
+	qpush(q, "Elizabeth II");
+	qpush(q, "Sheikh Sabah Al-Ahmad Al-Jaber Al-Sabah");
+	qpush(q, "Paul Biya");
+	qpush(q, "Michel Aoun");
+	qpush(q, "Mahmoud Abbas");
+	qpush(q, "Francis");
+
+	while (!qempty(q))
+		puts(qpop(q));
+
+	return 0;
+}
diff --git a/usth/ICT2.1/labwork/3/Ex3.c b/usth/ICT2.1/labwork/3/Ex3.c
new file mode 100644
index 0000000..b934ec0
--- /dev/null
+++ b/usth/ICT2.1/labwork/3/Ex3.c
@@ -0,0 +1,46 @@
+/*
+ * Interactive guessing game.
+ * This is free and unencumbered software released into the public domain.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include "stack.h"
+
+char *random10(char *c)
+{
+	char *p = malloc(sizeof(char));
+	*p = rand() % 10;
+	while (c != NULL && *p == *c) {
+		free(p);
+		p = malloc(sizeof(char));
+		*p = rand() % 10;
+	}
+	return p;
+}
+
+int main()
+{
+	stack *s = mkstack();
+	char guess, lost = 0;
+	srand(time(NULL));
+	stack_push(s, random10(NULL));
+STEP2:
+	stack_push(s, random10(stack_top(s)));
+	char *p = stack_pop(s);
+	puts(lost ? "Make another guess between 0 and 9"
+		  : "Make a guess between 0 and 9");
+	scanf("%hhd", &guess);
+	if ((guess - *p) * (guess - *(char *) stack_top(s)) < 0) {
+		puts("YOU WIN!");
+		return 0;
+	} else if (lost) {
+		puts("YOU LOSE!");
+		return 0;
+	}
+	
+	lost = 1;
+	goto STEP2;
+}
diff --git a/usth/ICT2.1/labwork/3/README.md b/usth/ICT2.1/labwork/3/README.md
new file mode 100644
index 0000000..a38ee6e
--- /dev/null
+++ b/usth/ICT2.1/labwork/3/README.md
@@ -0,0 +1,42 @@
+# Algorithms and Data Structures: Tutorial 3
+
+This package contains the following files:
+
+* `construct.h`, `construct.c`: Lisp construct (with `cons`, `car` and `cdr`)
+* `stack.h`, `stack.c`: initialization, check for empty, push, top and pop
+* `Ex1.c`: read from stdin and reverse the name
+* `Ex2.c`: add hard-coded names to a queue a print them to stdout
+* `Ex3.c`: interactive guessing game
+
+Compilation can be done as follows
+
+    cc construct.c stack.c Ex1.c -o Ex1
+    cc construct.c Ex2.c -o Ex2
+    cc construct.c stack.c Ex3.c -o Ex3
+
+All source files are as licensed under the Unlicense which states
+
+> This is free and unencumbered software released into the public domain.
+>
+> Anyone is free to copy, modify, publish, use, compile, sell, or
+> distribute this software, either in source code form or as a compiled
+> binary, for any purpose, commercial or non-commercial, and by any
+> means.
+>
+> In jurisdictions that recognize copyright laws, the author or authors
+> of this software dedicate any and all copyright interest in the
+> software to the public domain. We make this dedication for the benefit
+> of the public at large and to the detriment of our heirs and
+> successors. We intend this dedication to be an overt act of
+> relinquishment in perpetuity of all present and future rights to this
+> software under copyright law.
+>
+> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+> EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+> MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+> IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+> OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+> ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+> OTHER DEALINGS IN THE SOFTWARE.
+>
+> For more information, please refer to <http://unlicense.org/>
diff --git a/usth/ICT2.1/labwork/3/TT3.pdf b/usth/ICT2.1/labwork/3/TT3.pdf
new file mode 100644
index 0000000..708d20a
--- /dev/null
+++ b/usth/ICT2.1/labwork/3/TT3.pdf
Binary files differdiff --git a/usth/ICT2.1/labwork/3/construct.c b/usth/ICT2.1/labwork/3/construct.c
new file mode 100644
index 0000000..887b6d8
--- /dev/null
+++ b/usth/ICT2.1/labwork/3/construct.c
@@ -0,0 +1,26 @@
+/*
+ * Lisp construct implementation.
+ * This is free and unencumbered software released into the public domain.
+ */
+
+#include <stdlib.h>
+
+#include "construct.h"
+
+construct *cons(void *first, construct *rest)
+{
+	construct *list = malloc(sizeof(construct));
+	list->car = first;
+	list->cdr = rest;
+	return list;
+}
+
+void *car(construct *list)
+{
+	return list->car;
+}
+
+construct *cdr(construct *list)
+{
+	return list->cdr;
+}
diff --git a/usth/ICT2.1/labwork/3/construct.h b/usth/ICT2.1/labwork/3/construct.h
new file mode 100644
index 0000000..35d2448
--- /dev/null
+++ b/usth/ICT2.1/labwork/3/construct.h
@@ -0,0 +1,14 @@
+/*
+ * Lisp construct header.
+ * This is free and unencumbered software released into the public domain.
+ */
+
+typedef struct list construct;
+struct list {
+	void *car;
+        construct *cdr;
+};
+
+construct *cons(void *, construct *);
+void *car(construct *);
+construct *cdr(construct *);
diff --git a/usth/ICT2.1/labwork/3/stack.c b/usth/ICT2.1/labwork/3/stack.c
new file mode 100644
index 0000000..708fb59
--- /dev/null
+++ b/usth/ICT2.1/labwork/3/stack.c
@@ -0,0 +1,39 @@
+/*
+ * Stack implemented using linked list.
+ * This is free and unencumbered software released into the public domain.
+ */
+
+#include <stdlib.h>
+
+#include "stack.h"
+
+stack *mkstack()
+{
+	stack *s = malloc(sizeof(stack));
+	s->stack = NULL;
+	return s;
+}
+
+int stack_empty(stack *s)
+{
+	return s->stack == NULL;
+}
+
+void stack_push(stack *s, void *item)
+{
+	s->stack = cons(item, s->stack);
+}
+
+void *stack_top(stack *s)
+{
+	return car(s->stack);
+}
+
+void *stack_pop(stack *s)
+{
+	void *first = car(s->stack);
+	construct *rest = cdr(s->stack);
+	free(s->stack);
+	s->stack = rest;
+	return first;
+}
diff --git a/usth/ICT2.1/labwork/3/stack.h b/usth/ICT2.1/labwork/3/stack.h
new file mode 100644
index 0000000..2ed8851
--- /dev/null
+++ b/usth/ICT2.1/labwork/3/stack.h
@@ -0,0 +1,16 @@
+/*
+ * Stack header.
+ * This is free and unencumbered software released into the public domain.
+ */
+
+#include "construct.h"
+
+typedef struct {
+	construct *stack;
+} stack;
+
+stack *mkstack();
+int stack_empty(stack *);
+void stack_push(stack *, void *);
+void *stack_top(stack *);
+void *stack_pop(stack *);