/* Decimal to binary conversion uses stack */
#include <stdio.h>
#include <conio.h>
void main ( )
{
int stack[30], dec, rem, top=0;
clrscr();
printf ("\nEnter decimal number:\n");
scanf("%d", &dec);
while (dec!=0)
{
rem=dec%2;
top++;
stack[top]=rem;
dec=dec/2;
}
printf ("\nThe equivalent binary number is\n");
for (; top>0; top--)
{
printf ("%d", stack[top]);
}
getch ( );
}
/* Towers of Hanoi problem using recursion */
#include<stdio.h>
#include<conio.h>
void main()
{
int n;
char A='A',B='B',C='C';
void hanoi(int, char, char, char);
clrscr();
printf ("Enter Number of Disks:");
scanf("%d",&n);
printf("\n\n Tower of Hanoi problem with %d disks\n",n);
printf("Sequence is :\n");
hanoi (n, A, B, C);
printf ("\n");
getch();
}
void hanoi(int n, char A, char B, char C)
{
if (n!=0)
{
hanoi (n-1,A,C,B);
printf ("Move disk %d from %c to %c\n",n,A,C);
hanoi (n-1,B,A,C);
}
}
/* Convert Infix Expression into Postfix Expression
*/
#include<stdio.h>
#include<conio.h>
#include<string.h>
char stack [30];
int top = -1;
void infix_to_postfix (char *);
void push(char);
char pop ( );
void main ( )
{
char infix [30];
clrscr();
printf ("\n Enter the infix expression:\n");
gets (infix);
infix_to_postfix (infix);
getch ( );
}
void push (char sym)
{
if (top >= 29)
{
printf ("\n stack is overflow");
getch ( );
return;
}
else
{
top = top + 1;
stack [top] = sym;
}
}
char pop ( )
{
char i;
if (top ==-1)
{
printf ("\n stack is empty");
return(0);
}
else
{
i = stack [top];
top = top - 1;
}
return (i);
}
int prec (char ch)
{
if (ch=='^')
{
return (5);
}
else if (ch=='*' || ch=='/')
{
return (4);
}
else if (ch=='+' || ch=='-')
{
return (3);
}
else
{
return (2);
}
}
void infix_to_postfix (char infix [ ])
{
int length;
static int index = 0, pos= 0;
char symbol, temp;
char postfix [50];
length = strlen(infix);
while (index < length)
{
symbol = infix[index];
switch (symbol)
{
case '(' : push (symbol);
break;
case ')' : temp = pop ( );
while (temp != '(')
{
postfix [pos]=temp;
pos++;
temp=pop ();
}
break;
case '+' :
case '-' :
case '*' :
case '/' :
while (prec (stack[top]) >= prec (symbol))
{
temp = pop();
postfix [pos]= temp;
pos++;
}
push (symbol);
break;
default:postfix [pos++] = symbol;
break;
}
index++;
}
while (top>=0)
{
temp = pop ( );
postfix [pos++] = temp;
}
postfix [pos++] = '\0';
printf("\nEquivalent postfix expression is:\n");
puts (postfix);
return;
}
/* Program to Evaluate Postfix Notation */
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main( )
{
char S[80];
int i, top=-1, n, x=0, y=0, stack[80];
clrscr ( );
printf ("\n Enter the valid postfix notation :");
gets(S);
n = strlen(S);
printf ("The value of the postfix notation is :");
for (i=0;i<n; i++)
{
switch (S[i])
{
case '+' :
y=stack[top];
x=stack[top-1];
top = top-1;
x=x+y;
stack[top] = x;
break;
case '-' :
y=stack[top];
x=stack[top-1];
top = top-1;
x=x-y;
stack[top] = x;
break;
case '*' :
y=stack[top];
x=stack[top-1];
top = top-1;
x=x*y;
stack[top] = x;
break;
case '/' :
y=stack[top];
x=stack[top-1];
top = top-1;
x=x/y;
stack[top] = x;
break;
default :
top = top+1;
if (S[i]>=48 && S[i]<=57)
x = S[i] - 48;
stack[top] = x;
x=0;
}
}
printf("%d", stack[top]);
getch( );
}
