Data Structure And Algorithm MUST KNOW PROBLEMS (Uses Java as example language)

Question 1

How many ASCII Characters are there?

Now, write an algorithm for populating an array with every character (use Java as example language)

Answer 1

There are 256 ASCII characters.
//Java code to print every char in order:
int i = 0;
while(i <= 255) {
    System.out.println((char)i + " = " + i);
    i++;
}

Question 2

What is the formula for radial opposite? This is the opposite of a given integer on circle of m integers along its circumfrence. Eg: if circle is 10 in circumfrence, and provided i = 1 as input, then output 6.

Answer 2

import java.util.*;

 class Dcoder
 {
   public static void main(String args[])
   { 
    Scanner sc = new Scanner(System.in);
    String s1 = sc.next();
    String s2 = sc.next();
    int x = Integer.parseInt(s1);
    int y = Integer.parseInt(s2);
    int opposite = ((x/2)+y)%x; 
    System.out.println(opposite);
   }
 }

Answer: ((x/2)+y)%x;

Question 3

What is the distance formula for a coordinate grid? Convert this statement to code in Java.

Hint: Distance formula is the distance from any one point to another on a coordinate grid.

Answer 3

Math.sqrt((Y2-Y1)^2 + (X2-X1)^2)

Question 4

Formula to find all prime numbers up to N:

Recommendation: Make an isPrime method to handle the inner loop.

Answer 4

class Dcoder {
   public static void main(String args[])   { 
    Scanner sc = new Scanner(System.in);
    int M = Integer.parseInt(sc.next());
    int N = Integer.parseInt(sc.next());
    while(M <= N) {
      if(isPrime(M)) {
        System.out.println(M);
      }
      M++;
    }
   }
   static boolean isPrime(int M) {
     if(M ==0 || M == 1) {
       return false;
     }
     int k = 2;
     while(k < M) {
       if(M%k == 0) {
         return false;
       }
       k++;
     }
     return true;
   }
 }

Question 5

FizzBuzz

Answer 5

a

Question 6

Print all Primes

Answer 6

p

Question 7

Fibbonacci

Answer 7

f

Question 8

Remove Duplicates

Answer 8

r

Question 9

Minimum USD Coin Change

Answer 9

c

Question 10

Remove the Nth from the last node in a linked list.

Answer 10

r

Question 11

Reverse a Linked List

Answer 11

r

Question 12

Minimum Coin Change with ANY Coins

Answer 12

m

Question 13

Convert Roman numerals to decimal

Answer 13

c

Question 14

Shortest Distance to Char in a string

Answer 14

s

Question 15

Shift an array left by d shifts

Answer 15

s

Question 16

Determine whether two strings are permutations of each other

Answer 16

p

Question 17

Maximum Sub Array (Kadane’s Algorithm)

Answer 17

s