1 introduction to c c++ programming+adt

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Data Structures & Algorithms

Mugurel Ionuì Andreica

Spring 2010



Grading

� Activity during the Laboratory ± 20%

� Homework Assignments ± 30% ± Must be presented at the laboratory

� Tests during the Lectures ± 10% (bonus)

� Exam ± 50%

� If you¶re repeating the class ± Activity during the Laboratory ± 5%

� Activity during previous years can be counted towards this grade (please talk to meduring the breaks)

± Homework Assignments ± 45%� Must still be presented at the laboratory

± Tests during the Lecture ± 10% (bonus) ± Exam ± 50%

� Must obtain at least 25% of the final grade (from Lab Activity + Homework Assignments + Course Attendance) in order to be allowed to participate inthe exam



Course Topics

� Introduction to C/C++ Programming

� Abstract Data Type ± concept

� Stack

� Queue� Dynamic Memory Allocation

� Linked Lists

� Graphs

� Hash Tables� Trees

� Binary Search Trees

� Heaps



Introduction to C/C++ Programming

� Similar to Java

� The basic structure of a C program: ± Inclusion of headers

± Definition of types/classes

± Declaration of global variables

± Definition of functions

± The main function

� Similarities to the structure of a Java program: ± Inclusion of headers is similar to importing packages or classes

± C++ classes may contain both variables (fields) and functions withpublic/private/protected access specifications

� Differences from the structure of a Java program: ± Functions and variables may also be defined outside of a class

± The main function is not part of a class

± Arrays can also be allocated statically in C/C++



Example of a C/C++ Program

#include <stdio.h> // inclusion of the stdio.h header

int a, b, c; // global variables of the type int: a, b, c

int main() { // beginning of the main functiona = 10;

scanf("%d", &b); // read the value of b from the standard input

c = a + b; // assign the sum of a and b to the variable c

printf("%d\n", c); // print the value of c to the standard output

return 0; // finish the main function successfully

}



Common C/C++ Types� Basic types

± int

± char

± float

± double

± void ± only for function return values

� Structured data types

± struct s { int x; char y[2], z; double w };� Classes

� Pointer types ± int*, int**, ...

± char*, char**, ...

± float*, float**, ...

± double*, double**, ...

± void*, void**, ...

± Pointers to structs ± Pointers to classes

� Defining (multidimensional) arrays ± int v[100] // a static array named v with 100 elements, from 0 to 99

± int u[100][150], v[10][20][30], w[10][20][30][40], ...

± char u[100], v[10][20], w[10][20][30], ...

± float u[100], v[10][20], w[10][20][30], ...

± struct s u[100], v[10][20], w[10][20][30], ...

± ...



Commonly Used Headers

� stdio.h ± I/O functions

± scanf(format, ...) ± used for reading data� format=a string containing characters or format specifiers

± %d ± int

± %f ± float ± %lf ± double

� variations: fscanf, sscanf

± printf(string_with_format, ...) ± used for printing data� string_with_format=a string containing characters and format specifiers

± %d ± int

± %.4f ± prints a float with 4 decimal places

± %.4lf ± print a double with 4 decimal places

� variations: fprintf, sprintf

� stdlib.h ± Functions for dynamic memory allocation

� string.h ± Functions for string processing



C/C++ Programs using Arrays

int a[100];

int i, n;

int main() {

a[2] = 3; // is it correct ?a[99] = 6; // is it correct ?

a[100] = 5; // is it correct ?

a[101] = 13; // is it correct ?

n = 50;

for (i = 0; i < n; i++)a[i] = 2*i;

return 0;

}

#include <stdio.h>

double a[100], b[100], c[100];

int i, n;

int main() {scanf(³%d´, &n);

for (i = 0; i < n; i++) scanf(³%lf´, &a[i]);

for (i = 0; i < n; i++) scanf(³%lf´, &b[i]);

for (i = 0; i < n; i++) c[i] = a[i] + b[i];

for (i = 0; i < n; i++) printf(³%.3lf ³, c[i]);printf(³\n´);

return 0;

}



Bubble-Sort & Selection Sort#include <stdio.h>

float a[100];

int i, n, sw;

int main() {

scanf(³%d´, &n);

for (i = 0; i<n; i++) scanf(³%f´, &a[i]);

sw = 1;

while (sw) {

sw = 0;

for (i = 0; i < n - 1; i++)

if (a[i] > a[i + 1]) { // swap a[i] and a[i+1]

// option 1 - is this correct ?

a[i + 1] = a[i]; a[i] = a[i + 1];// option 2 - is this correct ?

float x = a[i]; a[i] = a[i+1]; a[i+1] = x;

sw = 1;

}

}

return 0;

}

#include <stdio.h>

float a[100];

int i, j, n;

int main() {

scanf(³%d´, &n);

for (i = 0; i<n; i++) scanf(³%f´, &a[i]);

for (i = 0; i < n; i++) {

int vmin_poz = i;

for (j = i + 1; j < n; j++)

if (a[j] < a[vmin_poz])

vmin_poz = j;

// swap a[i] and a[vmin_poz]

float x = a[i];

a[i] = a[vmin_poz];

a[vmin_poz] = x;

}

return 0;

}



Insertion Sort & Matrix

Multiplication#include <stdio.h>

double a[100];

int i, j, k, n;

int main() {

scanf(³%d´, &n);

for (i = 0; i<n; i++) scanf(³%lf´, &a[i]);

for (i = 1; i < n; i++) // why i=1 ?

for (j = 0; j < i; j++)

if (a[i] < a[j]) {

double x = a[i]; // really needed ?

// option 1 ± is this correct ?

for (k = j + 1; k <= i; k++) a[k] = a[k - 1];

// option 2 ± is this correct ?

for (k = i; k >= j+1; k--) a[k] = a[k - 1];

a[j] = x;

break;

}

// if, in the end, j == i => no insertion

return 0;}

#include <stdio.h>

#include <string.h>

#define NMAX 100

double a[NMAX][NMAX], b[NMAX][NMAX], c[NMAX][NMAX];

int i, j, k, n;

int main() {

scanf("%d", &n);

for (i = 0; i < n; i++) for (j = 0; j < n; j++) scanf("%lf", &a[i][j]);

for (i = 0; i < n; i++) for (j = 0; j < n; j++) scanf("%lf", &b[i][j]);

memset(c, 0, sizeof(c));

for (i = 0; i < n; i++)

for (j = 0; j < n; j++)

for (k = 0; k < n; k++)

c[i][j] += a[i][k] * b[k][j];

// question: does changing the order of the fors still produce

// a correct result ? (there are 3!=6 possible orderings)

// ex.1: for (k=0;k<n;k++) for (i=0;i<n;i++) for(j=0;j<n;j++)

// ex.2: for (i=0;i<n;i++) for (k=0;k<n;k++) for(j=0;j<n;j++)

return 0;

}



The struct Data Type

� struct struct_name {

variables (fields of the struct type)

}

� Examples:

± struct mystruct { int x; double y[10], z; float w; };

struct mystruct a, b[10], c[20][30];

a.x=3; b[2].y[3]=0.7; c[3][5].w=1.1; ± struct mystruct2 { int x; struct mystruct y; };

struct mystruct2 a, b[10], c[20][30];

a.x=3; b[2].y.x=4; c[3][5].y.y[3]=0.5;



Sample C/C++ Programs

#include <stdio.h>

struct s {

int u;

char z[89];

}

struct s a[4][5][6][7];

int main() {

int i, j, k, l, m;

for (i = 0; i < 4; i++)

for (j = 0; j < 5; j++)

for (k = 0; k < 6; k++)

for (l = 0; l < 7; l++) {

scanf("%d", &a[i][j][k][l].u);

for (m = 0; m < 89; m++)a[i][j][k][l].z[m] = 'a' + (m % ('z'-'a'+1));

}

return 0;

}

#include <stdio.h>

#include <math.h>

struct point {

double x, y; };

struct point v[100];

int i, j, k, n;

int main() {

scanf("%d", &n);

for (i = 0; i < n; i++) scanf("%lf %lf", &v[i].x, &v[i].y);

for (i = 0; i < n; i++)

for (j = i + 1; j < n; j++)

for (k = j + 1; k < n; k++) {

double area = 0.5 * fabs(v[i].x * v[j].y - v[i].y * v[j].x +v[j].x * v[k].y - v[j].y * v[k].x +

v[k].x * v[i].y - v[k].y * v[i].x);

printf("The area of the triangle (%d,%d,%d) is %.4lf\n", i, j, k, area);

}

return 0;

}



Functions

� return_type function_name(type1 pname1, type2 pname2,..., typen pnamen) {

body of the function

}

� Examples: ± int sum(int a, int b) { return a+b; } ± int isPrime(int x) {

for (int i = 2; i*i <= x; i++)

if (x % i == 0) return 0;

return 1;

} ± int factorial(int n) {

if (n <= 1) return 1; else return n*factorial(n-1); }

± int gcd(int a, int b) {

if (b == 0) return a; else return gcd(b, a % b); }

± double mult(double x, double y) { return x*y; }



C/C++ Programs using Functions

#include <stdio.h>

double u[100], v[100], sum[100];

void readArrays(double a[], double b[], int n) {

int i;

for (i = 0; i < n; i++)

scanf("%lf", &a[i]);

for (i = 0; i < n; i++)scanf("%lf", &b[i]);

}

void addArrays(double a[], double b[], double c[], int n) {

int i;

for (i = 0; i < n; i++)

c[i] = a[i] + b[i];

}

int main() {

int n;

scanf("%d", &n);

readArrays(u, v, n);

addArrays(u, v, sum, n);

return 0;

}

#include <stdio.h>

#include <math.h>

struct point {

double x, y; };

double area(struct point p1, struct point p2, struct point p3) {

return 0.5 * fabs(p1.x * p2.y - p1.y * p2.x +

p2.x * p3.y - p2.y * p3.x +p3.x * p1.y - p3.y * p1.x);

}

struct point v[100];

int i, j, k, n;

int main() {

scanf("%d", &n);for (i = 0; i < n; i++) scanf("%lf %lf", &v[i].x, &v[i].y);

for (i = 0; i < n; i++)

for (j = i + 1; j < n; j++)

for (k = j + 1; k < n; k++)

printf("The area of the triangle (%d,%d,%d) is %.4lf\n", i,

j, k, area(v[i], v[j], v[k]));

return 0;

}



The Fibonacci Sequence

#include <stdio.h>

int numCalls = 0;

int fibo(int n) {

numCalls++;

if (n <= 1)

return 1;

else

return fibo(n-1) + fibo(n-2);

}

int main() {

int n;

scanf("%d", &n);

printf("Fibonacci(%d)=%d\n", n, fibo(n));

printf("Total number of calls=%d\n", numCalls);

return 0;

}

#include <stdio.h>

#define NMAX 50

int numCalls = 0;

int memoFib[NMAX];

int fibo(int n) {

numCalls++;

if (memoFib[n] >= 0)return memoFib[n];

if (n <= 1)

return (memoFib[n] = 1);

else

return (memoFib[n] = fibo(n-1) + fibo(n-2));

}

int main() {

int i, n;

scanf("%d", &n);

for (i = 0; i <= n; i++) memoFib[i] = -1;


printf("Total number of calls=%d\n", numCalls);

return 0;}

� F(0)=F(1)=1

� F(n�2)=F(n-1)+F(n-2)

� 1, 1, 2, 3, 5, 8, 13, ...

V1

V2



The Fibonacci Sequence (cont.)� V1

± Fibonacci(20) = 10946

± numCalls = 21891

� Tree of Calls for V1 (n=4) :

� V2 ± Fibonacci(20) = 10946

± numCalls = 39

� Tree of Calls for V2 (n=4) :



The Fibonacci Sequence (cont.)

� What if we change theorder of the callsfibo(n-1) and fibo(n-2)? ± We use: fibo(n-2) +

fibo(n-1)

± Does the resut change? (V1, V2)

± Does the total number of calls change ? (V1,V2)

� A non-recursivefunction on the right

#include <stdio.h>

int fibo(int n) {

int i, fminus1, fminus2, fcurr;

fminus1 = 1;

fcurr = 1;

i = 1;

while (i < n) {

i++;

fminus2 = fminus1;

fminus1 = fcurr;

fcurr = fminus1 + fminus2;

}

return fcurr;

}

int main() {

int i, n;

scanf("%d", &n);


return 0;}

V3



Classes in C++

� class class_name {

access_specifier_1:

members;

methods;

access_specifier_2:members;

methods;

...

constructor // same name as the class

destructor // ~class_name}

� Access specifier = public / private / protected

� A class may contain variables and methods



Sample C++ Program with Classes

#include <stdio.h>

class MyClass {

private:

int x, cnt;

double v[100];

public:int y;

void setX(int value) {

x = value; }

int getX() {

return x; }

void addToV(int value) {v[cnt] = value;

cnt++; }

double getFromV(int pos) {

return v[pos]; }

MyClass(int value) {

printf("Calling the constructor\n");

x = value;

cnt = 0; }

~MyClass() {

printf("Calling the destructor\n");}};

int main() {

int i;

MyClass c(7);

printf("%d\n", c.getX());

c.setX(19);

c.y = 17

printf("%d\n", c.getX());

for (i = 0; i < 10; i++) c.addToV((double) i);

for (i = 9; i >= 0; i--)

printf("%.3lf\n", c.getFromV(i));

return 0;

}



Abstract Data Type

� A collection of axioms + operations

� Operations = what actions can be performed upon thedata type (implemented as functions in C/C++) ± for each operation we know:

� its name� its arguments (types and, possibly, names)

� its return type

� Axioms specify connections between operations (i.e. theoperations are related to one another)

� Does not contain information regarding theimplementation of the operations

� Similar to a Java interface (except that only theoperations are specified in an interface and no axioms)



Abstract Data Types - examples

� Stack

± Operations: push, pop, peek, isEmpty

± Axioms: a pop() call returns the argument x of the most

recent push(x) operation called on the data type for which no corresponding pop() has been called before

(or an error, otherwise)

� Queue

± Operations: enqueue, dequeue, peek, isEmpty ± Axioms: a dequeue() call returns the argument x of the

oldest enqueue(x) call for which no corresponding

dequeue() was called (or an error, otherwise)



From Abstract Data Types to Data

Structures

� Data structures will be initially handled as abstract datatypes

� First we will specify the operations and axioms (many

times, the axioms will be given implicitly)� Then we will discuss possible implementations(occasionally more than just one)

� Data structures store elements ± Sometimes, the elements may have any type

± Other times, the elements must obey some specific properties(e.g. they must be comparable)

� In order to store any type of elements => we will useclass t em pl at es (in C++)



Class Templates

� t em pl at e<ty pename T> class class_name { ... } ± A normal class definition will be pref i xed by

t em pl at e<ty pename T>

± The type T can now be used as a valid type within theclass

� we can have variables, function arguments and functionreturn values of type T

� The class cl ass_name is par amet er iz ed with thetype T

� Most of the times: T=the type of the elementsstored by the data structure

� Similar to Java generics



Class Templates - Example

#include <stdio.h>

template<typename T> class MyGenericContainer {

private:

T privateObject;

public:

void setPrivateObject(T value) {

privateObject = value;}

T getPrivateObject() {

return privateObject;

}

MyGenericContainer(T value) {

privateObject = value;}

};

struct mystruct {

int x;

char y[32];

double z;

};

int main() {

MyGenericContainer<int> c1(7);

printf("%d\n", c1.getPrivateObject());

c1.setPrivateObject(9);

printf("%d\n", c1.getPrivateObject());

MyG

enericContainer<double> c2(7.9);printf("%.3lf\n", c2.getPrivateObject());

c2.setPrivateObject(9.902);

printf("%.3lf\n", c2.getPrivateObject());

struct mystruct a;

a.x = 3; a.y[4] = 'z'; a.y[5] = 90;

a.z = 90.234;

MyGenericContainer<struct mystruct> c3(a);

printf("%.3lf\n", (c3.getPrivateObject()).z);

a.z++;

c3.setPrivateObject(a);

printf("%.3lf\n", (c3.getPrivateObject()).z);

return 0;

}

1 introduction to c c++ programming+adt

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