What is the output ?

6. Give sizeof(a) in bytes for the following: (assume 32bit PC)

char *a[10];
char (*a)[10];
char (**a)[20];
char (*a)(int x, char c);

Ans: 40 , 4 , 4 , 4

7. Find out the output :

#include<stdio.h>
main()
{
    int n1 = 10, n2 = 12;
    if( n2=!0)
        printf("Result is:%d\n",(n1/n2));
    else
        printf("cannot divide by zero\n");
}
Ans: Result is:10

8. Find out the output:

#include<stdio.h>
main()
{
    long int one_million;
    one_million=1,000,000;
    printf("One million is %d",one_million);
}
Ans: One million is 1

9.  what is the output ?

#include<stdio.h>
#define f(a,b) a##b
#define g(a) #a
#define h(a) g(a)
main()
{
    printf("%s %s\n",h(f(1,2)),g(f(1,2)));
}
Ans: 12 f(1,2)

10. what is the output?

#include<stdio.h>
main()
{
    static int j=printf("%d",456);;
    printf("%d",j);
}
Ans: Error

11. What is the output ?

#include<stdio.h>
main()
{
int i = 5;
int j;
j=sizeof(i++);
printf("%d",i);
}
Ans: 5

12. What is the output of z?

#include<stdio.h>
main()
{
int z,x=5,y=-10,a=4,b=2;
z=x++ - --y * b / a;
}
Ans: 10

What is the output ?

1. what is the output of the following program ? “alloc failed or alloc successful” ?

#include<stdio.h>
void alloc(int *p)
{
p=(int*)malloc(10*sizeof(*p));

}
main()
{
int *p=NULL;
alloc(p);
if(NULL==p)
printf("alloc failed");
else
printf("alloc successful");
}
Ans: alloc failed

make changes to get “alloc successful” as output.

2. what is the output of the program ?

#include<stdio.h>
main()
{
    struct node
    {
            int a;
            int b;
            int c;
    };
    struct node s={3,5,6};
    struct node *pt=&s;
    printf("%d",*(int*)pt);
    }
Ans: 3

3.  what is the output of the following program ?

#include<stdio.h>
main()
{
    printf(3+"Hello World");
    }
Ans: lo World

4. what is the output of the following program ?

#include<stdio.h>
main()
{
    int a=0;
    if(a=2)
    printf("I am inside IF\n");
    printf("It is correct");
    }
Ans:

I am inside IF
It is correct

5. what is the output ?

#include<stdio.h>
main()
{
    unsigned i=5;
    if(i > -5)
        printf("it is less than -5");
}
Ans: No output

SORTING COMPLEXITIES

 

SORTING	BEST CASE	AVERAGE CASE	WORST CASE
Insertion Sort	O(n)	O(n2)	O(n2)
Bubble Sort	O(n)	O(n2)	O(n2)
Selection Sort	O(n2)	O(n2)	O(n2)
Quick Sort	O(n log n)	O(n log n)	O(n2)
Merge Sort	O(n log n) typically , O(n)	O(n log n)	O(n log n)
Heap Sort	O(n log n)	O(n log n)	O(n log n)
Radix Sort	O(kn)	O(kn)	O(kn)
Counting Sort	O(n+k)	O(n+k)	O(n+k)

PLACEMENT QUESTIONS–I

 

Here I post some of the placement questions. These are very simple..

Question 1 : Ugly numbers are numbers whose only prime factors are 2, 3 or 5. 
The sequence
1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, ...
shows the first 11 ugly numbers.
By convention, 1 is included.

Write a program to find and print the 1500'th ugly number.

Question 2 : int main()
{
int i, n = 20;
for (i = 0; i < n; i--)
printf("*");
return 0;
}

Change/add only one character and print '*' exactly 20 times.
(there are atleast 3 solutions to this problem)

Question 3 : You are provided with two stacks, and pop() and push() 
functions for them.
You have to implement queue i.e. enqueue() and dequeue() using the
available operations.

Question 4 : How do you reverse the words in a string?

"My name is Ajit Agarwal"
to
"Agarwal Ajit is name My"

A O(n) and 'in space' solution is appreciable.

Question 5 : Given an array of numbers, except for one number all the others, 
occur twice. 
Give an algorithm to find that number which occurs only once in the
array.

Question 6 : There is a series of numbers in ascending order. All these numbers
have the same number of binary 1s in them. Given the number of 1 bits set in
the numbers, write an algorithm/C program to find the nth number in
the series.

Question 7 : Given a string s1 and a string s2, write  a snippet to say 
whether s2 is a rotation of s1 using only one 
call to strstr routine?

(eg given s1 = ABCD and s2 = CDAB, return  true,
given s1 = ABCD, and s2 = ACBD , return false)

Question 8 : 

What's the  "condition" so that the following code
snippet  prints both HelloWorld !

if  "condition"
printf ("Hello");
else
printf("World");

TREE PROBLEMS - II

1. Given two trees, return true if they are
structurally identical.

int sameTree(struct node* a, struct node* b) {
  // 1. both empty -> true
  if (a==NULL && b==NULL) return(true);

  // 2. both non-empty -> compare them
  else if (a!=NULL && b!=NULL) {
    return(
      a->data == b->data &&
      sameTree(a->left, b->left) &&
      sameTree(a->right, b->right)
    );
  }
  // 3. one empty, one not -> false
  else return(false);
}

2. code to count number of leaves in the tree

void count_leaf(mynode *root)
{
   if(root!=NULL)
   {
      count_leaf(root->left);
      if(root->left == NULL && root->right==NULL)
      {
        // This is a leaf!
        count++;
      }
      count_leaf(root->right);
   }
}

3. code to create copy of tree

mynode *copy(mynode *root)
{
  mynode *temp;
  if(root==NULL)return(NULL);
  temp = (mynode *) malloc(sizeof(mynode));
  temp->value = root->value;
  temp->left  = copy(root->left);
  temp->right = copy(root->right);
  return(temp);
}

4. code to create mirror copy of tree

mynode *copy(mynode *root)
{
  mynode *temp;
  if(root==NULL)return(NULL);
  temp = (mynode *) malloc(sizeof(mynode));
  temp->value = root->value;
  temp->left  = copy(root->right);
  temp->right = copy(root->left);
  return(temp);
}

5. Implementing level order traversal of a tree

If this is the tree,

        1
   2         3
5   6     7   8

its level order traversal would be

1 2 3 5 6 7 8


void levelOrderTraversal(mynode *root)
{
  mynode *queue[100] = {(mynode *)0}; // Important to initialize!
  int size = 0;
  int queue_pointer = 0;
  while(root)
  {
      printf("[%d] ", root->value);
      if(root->left)
      {
        queue[size++] = root->left;
      }
      if(root->right)
      {
        queue[size++] = root->right;
      }
      root = queue[queue_pointer++];   
  }
}

books for interviews

These are the 2 important books for computer science students who are
attending interview.
1. Programming interview exposed
2. Do the new - career cup