DSAFREAKS PS-1 Program Notes

1. Pattern Programs

1. Rectangle Star Pattern

Code –

Java

C++

public class DSAFREAKS 
{ 
    public static void rightTriangle(int n, int m){
        for(int i = 1; i <= n; i++){ //outer loop for number of rows(n) 
            for(int j = 1; j <= m; j++){ //  inner loop for columns     
                System.out.print("* "); // print star
            }           
            System.out.println(); // ending line after each row
        } 
    } 
    public static void main(String args[]){ 
        int n = 5, m = 6; 
        rightTriangle(n, m); 
    } 
}

#include <iostream>
using namespace std;

void rightTriangle(int n, int m) {
    for (int i = 1; i <= n; i++) { 
        for (int j = 1; j <= m; j++) { 
            cout << "* "; 
        }
        cout << endl;
    }
}

int main() {
    int n = 5, m= 6;
    rightTriangle(n, m);
    return 0;
}

2. Right Triangle Star Pattern

Code –

Java

C++

public class DSAFREAKS 
{ 
    public static void rightTriangle(int n){
        for(int i = 1; i <= n; i++){ //outer loop for number of rows(n) 
            for(int j = 1; j <= i; j++){ //  inner loop for columns     
                System.out.print("* "); // print star
            }           
            System.out.println(); // ending line after each row
        } 
    } 
    public static void main(String args[]){ 
        int n = 5; 
        rightTriangle(n); 
    } 
}

#include <iostream>
using namespace std;

void rightTriangle(int n) {
    for (int i = 1; i <= n; i++) { 
        for (int j = 1; j <= i; j++) { 
            cout << "* "; 
        }
        cout << endl;
    }
}

int main() {
    int n = 5;
    rightTriangle(n);
    return 0;
}

3. Downward Triangle Star Pattern

Code –

Java

C++

public class DSAFREAKS{
    public static void main(String[] args){
      int rows = 5;
      for (int i = rows; i >= 1; i--){
        for (int j = 1; j <= i; j++){
          System.out.print("* ");
        }
        System.out.println();
      }
    }
}

#include <iostream>
using namespace std;

int main() {
    int rows;
    cin>>rows;
    for (int i = rows; i >= 1; i--) {
        for (int j = 1; j <= i; j++) {
            cout << "* ";
        }
        cout << endl;
    }
    return 0;
}

4. Mirrored Right Triangle Star Pattern

Code –

Java

C++

public class Main 
{ 
    public static void printStars(int n) { 
        for(int i = 1; i <= n; i++){ //outer loop for number of rows(n) 
            for(int j = n-i; j >= 1; j--){ // inner loop for spaces 
                System.out.print("  "); // printing space
            } 
            
            for(int j = 1; j <= i; j++){ //  inner loop for columns
                System.out.print("* "); // print star
            }           
            System.out.println(); // ending line after each row
        }
    } 
    public static void main(String args[]) 
    { 
        int n = 5; 
        printStars(n); 
    } 
}

#include <iostream>
using namespace std;

void printStars(int n) {
    for (int i = 1; i <= n; i++) {
        for (int j = n - i; j >= 1; j--) {
            cout << "  ";
        }
        for (int j = 1; j <= i; j++) {
            cout << "* ";
        }
        cout << endl;
    }
}

int main() {
    int n = 5;
    printStars(n);
    return 0;
}

5. Right down Mirror Star Pattern

Code –

Java

C++

public class DSAFREAKS{
  public static void main(String[] args){
    int rows = 5;
    for (int i = rows; i >= 1; i--){
      for (int j = i; j < rows; j++){
        System.out.print(" ");
      }
      for (int j = 1; j <= i; j++){
        System.out.print("*");
      }
      System.out.println();
    }
  }
}

#include <iostream>
using namespace std;

int main(){
    int rows = 5;
    for (int i = rows; i >= 1; i--){
        for (int j = i; j < rows; j++){
            cout << " ";
        }
        for (int j = 1; j <= i; j++){
            cout << "*";
        }
        cout << endl;
    }
    return 0;
}

6. Pyramid Program

Code –

Java

C++

public class DSAFREAKS
{  
    public static void pyramidPattern(int n) {  
        for (int i = 1; i <= n; i++){ //outer loop for number of rows(n)   
        
            for (int j = 1; j <= n-i; j++){ //inner loop for spaces 
                System.out.print(" "); //print space
            }  
            for (int j = 1; j <= i; j++ ){ //inner loop for number of columns
                System.out.print("* "); //print star
            } 
  
            System.out.println(); //ending line after each row
        } 
    } 
  
    public static void main(String args[]) //driver function
    { 
        int n = 5; 
        pyramidPattern(n); 
    } 
}

#include <iostream>
using namespace std;

void printStars(int n) {
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n-i; j++) {
            cout << " ";
        }
        for (int j = 1; j <= i; j++) {
            cout << "* ";
        }
        cout << endl;
    }
}

int main() {
    int n = 5;
    printStars(n);
    return 0;
}

7. Reversed Pyramid Star Pattern

Code –

Java

C++

public class DSAFREAKS{
  public static void main(String[] args){
  
    int rows = 5;        
    for (int i = 1; i <= rows; i++){
      for (int j = 1; j < i; j++){
        System.out.print(" ");
      }
      for (int j = 1; j <= rows-i+1; j++){
        System.out.print("* ");
      }
      System.out.println();
    }
  }
}

#include <iostream>
using namespace std;

int main(){
  int rows = 5;
  for (int i = 1; i <= rows; i++){
    for (int j = 1; j < i; j++){
      cout<<" ";
    }
    for (int j = 1; j <= rows-i+1; j++){
      cout<<"* ";
    }
    cout<<endl;
  }
  return 0;
}

8. Diamond Shape Pattern Program in Java

Code –

Java

C++

public class Main{
  public static void main(String args[]){
    int n = 5, space = n-1;
    
    for (int i = 1; i <= n; i++){
      for (int j = 1; j<= space; j++){
        System.out.print(" ");
      }
      space--;
      for (int j = 1; j <= 2 * i - 1; j++){
        System.out.print("*");
      }
      System.out.println();
    }
    
    space = 1;
    for (int i = 1; i <= n - 1; i++){
      for (int j = 1; j <= space; j++){
        System.out.print(" ");
      }
      space++;
      for (int j = 1; j <= 2 * (n - i) - 1; j++){
        System.out.print("*");
      }
      System.out.println();
    }
  }
}

#include<iostream>

using namespace std;

int main() {
    int n = 5, space = n-1;
    
    for (int i = 1; i <= n; i++){
      for (int j = 1; j<= space; j++){
        cout << " ";
      }
      space--;
      for (int j = 1; j <= 2 * i - 1; j++){
        cout << "*";
      }
      cout << endl;
    }
    
    space = 1;
    for (int i = 1; i <= n - 1; i++){
      for (int j = 1; j <= space; j++){
        cout << " ";
      }
      space++;
      for (int j = 1; j <= 2 * (n - i) - 1; j++){
        cout << "*";
      }
      cout << endl;
    }
    return 0;
}

9. Hollow Triangle Star pattern

Code –

Java

C++

public class DSAFREAKS{
     public static void main(String[] args){
          int rows = 5;
          for (int i=1; i<= rows ; i++){
              for (int j = i; j < rows ; j++) {
                  System.out.print(" ");
              }   
              for (int k = 1; k <= (2*i -1) ;k++) {
                  if( k==1 || i == rows || k==(2*i-1)) {
                      System.out.print("*");
                  }
                  else {
                      System.out.print(" ");
                  }
              }
              System.out.println();
          }
      }
}

#include<iostream>

using namespace std;

int main() {
    int rows = 5;
    for (int i=1; i<= rows ; i++){
        for (int j = i; j < rows ; j++) {
            cout<<" ";
        }   
        for (int k = 1; k <= (2*i -1) ;k++) {
            if( k==1 || i == rows || k==(2*i-1)) {
                cout<<"*";
            }
            else {
                cout<<" ";
            }
        }
        cout<<endl;
    }
    return 0;
}

10. Simple number program

Code –

Java

C++

public class DSAFREAKS{
    public static void printNums(int n) { 
        int i, j,num; 
    
        for(i=0; i<n; i++) { 
            num=1; 
            for(j=0; j<=i; j++) {  
                System.out.print(num+ " "); 
                num++; 
            } 
            System.out.println(); 
        } 
    } 
    public static void main(String args[]){ 
        int n = 5; 
        printNums(n); 
    } 
}

#include<iostream>

using namespace std;

int main() {
    int 5;
    for(int i=0; i<n; i++) { 
        int num=1; 
        for(int j=0; j<=i; j++) {  
            cout<<num<<" ";
            num++; 
        } 
        cout<<endl;
    } 
    return 0;
}

11. Pattern 11

Code –

Java

C++

public class DSAFREAKS{            
    public static void main(String[] args) {
        int k = 1, n = 5;
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j< i + 1; j++) {
                System.out.print(k++ + " ");
            }
   
            System.out.println();
        }
    }
}

#include<iostream>

using namespace std;

int main() {
    int k = 1, n = 5;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j< i + 1; j++) {
            System.out.print(k++ + " ");
        }
 
        System.out.println();
    }
    return 0;
}

12. Diamond Pattern using Numbers

Code –

Java

C++

public class DSAFREAKS{            
    public static void main(String[] args) {
        for (int i = 1; i <= 4; i++){
            int n = 4;
   
            for (int j = 1; j<= n - i; j++) { 
                System.out.print(" "); 
            } 
            for (int k = i; k >= 1; k--){
                System.out.print(k);
            }
            for (int l = 2; l <= i; l++) { 
                System.out.print(l); 
            } 
            System.out.println(); 
        } 
        
        for (int i = 3; i >= 1; i--){
            int n = 3;
   
            for (int j = 0; j<= n - i; j++) { 
                System.out.print(" "); 
            } 
            for (int k = i; k >= 1; k--){
                System.out.print(k);
            }
            for (int l = 2; l <= i; l++){
                System.out.print(l);
            }
            System.out.println();
        }
    }
}

#include<iostream>

using namespace std;

int main() {
    int n = 4;
    for (int i = 1; i <= n; i++){

        for (int j = 1; j <= n - i; j++) { 
            System.out.print(" "); 
        } 
        for (int k = i; k >= 1; k--){
            System.out.print(k);
        } 
        for (int l = 2; l <= i; l++) { 
            System.out.print(l); 
        } 
        System.out.println(); 
    } 
        
    for (int i = 3; i >= 1; i--){
        int n = 3;
 
        for (int j = 0; j<= n - i; j++) { 
            System.out.print(" "); 
        } 
        for (int k = i; k >= 1; k--){
            System.out.print(k);
        } 
        for (int l = 2; l <= i; l++){
            System.out.print(l);
        } 
        System.out.println();
    }
    return 0;
}

13. Binary Number Pattern

Code –

Java

C++

public class DSAFREAKS{
    public static void main(String[] args) {
        int rows = 5;
        for (int i = 1; i <= rows; i++) {
            int num;
            if(i%2 == 0){
                num = 0;
                for (int j = 1; j <= rows; j++){
                    System.out.print(num);
                    num = (num == 0)? 1 : 0;
                }
            }
            else{
                num = 1;
                  
                for (int j = 1; j <= rows; j++){
                    System.out.print(num);
                      
                    num = (num == 0)? 1 : 0;
                }
            }
            
            System.out.println();
        }
    }
}

#include<iostream>

using namespace std;

int main() {
    int rows = 5;
    for (int i = 1; i <= rows; i++) {
        int num;
        if(i%2 == 0){
            num = 0;
            for (int j = 1; j <= rows; j++){
                cout<<num;
                num = (num == 0)? 1 : 0;
            }
        }
        else{
            num = 1;
            for (int j = 1; j <= rows; j++){
                cout<<num;
                num = (num == 0)? 1 : 0;
            }
        }
        cout<<endl;
    }
    return 0;
}

14. Pascal’s Triangle Program in Java

Code –

Java

C++

public class Main{            
    public static void main(String[] args) {
        int n = 5;
        for (int i = 0; i < n; i++) {
            for(int j = 1; j < n-i; j++){
                System.out.print(" ");
            }
            int number = 1;
            for (int j = 0; j <= i; j++) {
                System.out.print(number + " ");
                number = number * (i - j) / (j + 1);
            }
            System.out.println();
        }
    }
}

2. Basic logical problems

S.N	Topic	Problem Link	Solution 1
1	Swap Two Numbers	GFG	GFG
2	Check character is Vowel or consonant	GFG
3	Largest of three numbers	GFG
4	Check given year is leap year or not	GFG
5	Print Floyd’s Triangle	GFG
6	Convert decimal to binary	GFG
7	Sum of n natural numbers	GFG
8	Check prime number	GFG
9	Print all prime till N	GFG
10	Print Fibonacci Series till N	GFG
11	Count digits in a number ‘n’	GFG
12	Power of a number	GFG
13	Sum of digits of a number	GFG
14	Reverse a number ‘n’	GFG
15	Rotate a number by K	GFG
16	Factorial of a number	GFG
17	GCD/HCF of two numbers	GFG
18	LCM of two numbers	GFG
19	Number is palindrome or not	GFG
20	Check Armstrong number	GFG
21	Number is perfect or not	GFG
22	Decimal to any base	GFG
23	Any base to decimal	GFG
24	Any base to Any base	GFG

3. Arrays(1D/2D)

S.N	Topic	Problem Link
1	Find maximum/minimum elements	GFG
2	Print array in reverse order	GFG
3	Find element in an array	GFG
4	Average of all elements	GFG
5	Two Sum (Naive Approach)	GFG
6	Rotate an array	GFG
7	Bar chart using array elements
8	Read matrix from user	GFG
9	Add two matrices	GFG
10	Multiply two matrices	GFG
11	Transpose of matrix	Leetcode
12	Spiral of a matrix	GFG
13	Rotate a matrix	GFG
14	Ring Rotate a matrix	GFG
15	Saddle Point	GFG

4. Strings

S.N	Topic	Problem Link
1	Count number of words in string	GFG
2	Print all the substrings of a string
3	Program to remove all spaces from string	GFG
4	Check anagram of two strings	Leetcode
5	String is palindrome or not	Leetcode
6	Print all palindromic substrings	Leetcode
7	String Compression	Leetcode
8	Toggle every character	GFG

5. Time Complexity

6. Binary Search Algorithm

S.N	Topic	Problem Link
1	Search Target in Sorted array	Leetcode
2	Search Insert Position	Leetcode
3	Find First and Last Position of Element	Leetcode
4	Number of Occurrences	GFG
5	Ceil and Floor a number in sorted array	GFG
6	Find Minimum in Rotated Sorted Array	Leetcode
7	Search in Rotated Sorted Array	Leetcode
8	Find element index in infinite sorted array
9	Search Element in 2D Array	Leetcode
10	Search a 2D Matrix II	Leetcode
11	Find Peak Element	Leetcode
12	Find Peak Element in 2d Array	Leetcode
13	Koko eating bananas	Leetcode
14	Allocate Minimum Number Pages	GFG
15	Find Smallest Divisor	Leetcode
16	Capacity To Ship Packages Within D Days	Leetcode

7. Array Problems Part 2

S.N	Topic	Problem Link
1	Move Zeroes	Leetcode
2	Missing Number	Leetcode
3	Max Consecutive Ones	Leetcode
4	Largest subarray with sum equals K(Only Positives)
5	Sort an array of 0’s and 1’s	GFG
6	Sort an array of 0’s, 1’s and 2’s	Leetcode
7	Maximum sum subarray (Kadane’s Algorithm)	Leetcode
8	Majority Element	Leetcode
9	Majority Element II	Leetcode
10	Next Permutation	Leetcode
11	Set Matrix Zeroes	Leetcode
12	Maximum Product subarray	Leetcode

8. Recursion

1. Understand Recursion

S.N	Topic	Problem Link
1	Print Decreasing	GFG
2	Print Increasing	GFG
3	Print Increasing Decreasing
4	Factorial	GFG
5	Power(x, n) using recursion	Leetcode
6	Power(x, n) logarithmic	Leetcode
7	Understanding Euler Tree Representation
8	Sort an array using recursion	GFG
9	Sort an Stack using recursion	GFG
10	Tower of Hanoi	GFG

2. Choices Technique/Problems

S.N	Topic	Problem Link
1	Get Subsets	Leetcode
2	Get Stair Paths	GFG
3	Print Subsets	GFG
4	Print Stair Paths
5	Combination Sum I	Leetcode
6	Subset II	Leetcode
7	Combination Sum II	Leetcode
8

3. Backtracking

S.N	Topic	Problem Link
1	Print all paths in a 2d Array	GFG
2	N queens Problem	Leetcode
3	Sudoku Solver	Leetcode
4	Palindrome Partitioning	Leetcode
5	Word Search	Leetcode

9. Imp. Sorting Algorithms

S.N	Topic	Problem Link
1	Bubble Sort	GFG
2	Selection Sort	GFG
3	Insertion Sort	GFG
4	Merge Two Sorted Arrays	GFG
5	Merge Sort	GFG
6	Partition an Array	GFG
7	Quick Sort	GFG
8	Quick Select	GFG

10. Stack and Queues

S.N	Topic	Problem Link	Solution
1	Implement Stack using Array	GFG	Learn More
2	Implement Queue using Array	GFG	Learn More
3	Implement Stack using Queue	Leetcode
4	Implement Queue using Stack	Leetcode
5	Duplicate Brackets	GFG
6	Balanced Brackets	Leetcode
7	Next greater element to the right	Leetcode
8	Stock Span Problem	GFG
9	Largest area Histogram	Leetcode
10	Sliding Window Maximum	Leetcode
11	Infix Evaluation	Leetcode
12	Infix Conversion in Prefix and postfix
13	Postfix Evaluation and Conversion
14	Prefix Evaluation and Conversion
15	The Celebrity Problem	GFG
16	Merge Overlapping Intervals	Leetcode
17	Remove K Digits	Leetcode
18	Sum of subarray Minimums	Leetcode
19	Asteroid Collisions	Leetcode

11. Priority Queue/Heap

S.N	Topic	Problem Link
1	Kth Largest Element/K Largest Elements	Leetcode
2	Kth Smallest Element/ K Smallest Elements
3	Sort K Sorted Array	GFG
4	Merge K Sorted Arrays	GFG
5	Find Median from Data Stream	Leetcode
6	Kth Largest Element in a Stream	Leetcode
7	Top K Frequent Elements	Leetcode
8	Minimum cost of Ropes	GFG
9	Implement Priority Queue

12. HashMap/HashSet

S.N	Topic	Problem Link
1	Highest Frequency Character
2	Intersection of Two Arrays(No Duplicates)	Leetcode
3	Intersection of Two Arrays(With Duplicates)
4	Two Sum	Leetcode
5	Longest Consecutive Sequence	Leetcode
6	First repeating character	GFG
7	Subarray Sum equals K	Leetcode
8	Longest subarray with sum k	GFG
9	Longest substring without repeating characters	Leetcode
10	Uncommon Characters	GFG
11	Uncommon Words	Leetcode
12	Longest Subarray with equal 0’s and 1’s	GFG
13	Count Subarrays with equal 0’s and 1’s	GFG
14	Longest subarray with sum divisible by K	GFG
15	Longest Palindrome	Leetcode
16	Zero Sum Subarray	GFG
17	Equivalent Sub-Arrays	GFG
18	Count of substrings containing K ones	GFG
19	Valid Sudoku	Leetcode
20	HashMap Implementation

13. LinkedList

S.N	Topic	Problem Link
1	Introduction of Linked List
2	AddLast in Linked List
3	Display Linked List
4	Remove First From LinkedList
5	Get in Linked List
6	Add First in Linked List
7	Add at index in Linked List
8	Remove Last in Linked List
9	Remove at index in Linked List
10	Reverse Linked List (Data – Iterative)	Leetcode
11	Reverse Linked List (Pointer Iterative)	Leetcode
12	Reverse Linked List (Recursively)	Leetcode
13	Remove Kth node from end of the Linked List	Leetcode
14	Middle of the Linked List (Tortoise & Hare Method)	Leetcode
15	Merge Two Sorted Linked Lists	Leetcode
16	Merge Sort a Linked List	Leetcode
17	Remove Duplicates from Sorted List	Leetcode
18	Is Linked List Palindrome	Leetcode
19	Segregate odd even linked list	GFG
20	Add two numbers	Leetcode
21	Intersection of Two Linked List	Leetcode
22	Cycle detection in linked list	Leetcode
23	Starting point of Cycle	Leetcode
24	Rotate List	Leetcode
25	Copy List with Random Pointer	Leetcode
26	Reverse List in K-Group	Leetcode

14. Binary Tree

S.N	Topic	Problem Link
1	Binary Tree Introduction
2	Display a Binary Tree
3	Size, Sum, Max And Height of Binary Tree
4	Binary Tree Traversals(Pre, Post & In Order)
5	Iterative Pre order traversal	Leetcode
6	Iterative In Order Traversal	Leetcode
7	Iterative Post Order Traversal	Leetcode
8	Level Order Traversal	Leetcode
9	Root to Leaf Paths in binary tree	Leetcode
10	Find node and Node to Root Path in binary tree	GFG
11	Print K levels down	GFG
12	K distance from root	Leetcode
13	Clone a Binary Tree	GFG
14	Remove Leaf Nodes	Leetcode
15	Diameter of Binary Tree	Leetcode
16	Balanced Binary Tree	Leetcode
17	Zig Zag Level Order Traversal	Leetcode
18	Vertical Order Traversal	Leetcode
19	Left/Right View of Binary Tree	Leetcode
20	Top View of Binary Tree	GFG
21	Bottom View of Binary Tree	GFG
22	LCA of a Binary Tree	Leetcode
23	Maximum width of Binary Tree	Leetcode
24	Construct Binary Tree using Preorder and Inorder	Leetcode
25	Construct Binary Tree using Postorder and Inorder	Leetcode
26	Maximum Path sum in binary tree	Leetcode

15. Binary Search Tree

S.N	Topic	Problem Link
1	Binary Search Tree Introduction
2	Size and sum of BST
3	Find in BST	Leetcode
4	Max and min in BST
5	Add node in BST	Leetcode
6	Delete Node in BST	Leetcode
7	Add the sum of greater values	GFG
8	LCA of BST	Leetcode
9	Range sum of BST	Leetcode
10	Target Sum Pair in BST	Leetcode
11	Check if a Binary Tree is BST	Leetcode
12	Find Predecessor and Successor	GFG
13	Kth Smallest/Largest node	Leetcode

16. Sliding Window & Two pointer

S.N	Topic	Problem Link
1	Sum of all subarray of length K (Introduction)	GFG
2	Max/Min Sum of Subarrays With Length K	GFG
3	Maximum Sum of Distinct Subarrays With Length K	Leetcode
4	Find all Anagrams in a String	Leetcode
5	Sliding Window Maximum	Leetcode
6	Longest K unique characters substring	GFG
7	Longest Substring Without Repeating Characters	Leetcode
8	Max consecutive One III	Leetcode
9	Binary Subarrays With Sum	Leetcode
10

DSAFreaks PS-1 Program Notes

1. Pattern Programs

1. Rectangle Star Pattern

Code –

2. Right Triangle Star Pattern

Code –

3. Downward Triangle Star Pattern

Code –

4. Mirrored Right Triangle Star Pattern

Code –

5. Right down Mirror Star Pattern

Code –

6. Pyramid Program

Code –

7. Reversed Pyramid Star Pattern

Code –

8. Diamond Shape Pattern Program in Java

Code –

9. Hollow Triangle Star pattern

Code –

10. Simple number program

Code –

11. Pattern 11

Code –

12. Diamond Pattern using Numbers

Code –

13. Binary Number Pattern

Code –

14. Pascal’s Triangle Program in Java

Code –

2. Basic logical problems

3. Arrays(1D/2D)

4. Strings

5. Time Complexity

6. Binary Search Algorithm

7. Array Problems Part 2

8. Recursion

1. Understand Recursion

2. Choices Technique/Problems

3. Backtracking

9. Imp. Sorting Algorithms

10. Stack and Queues

11. Priority Queue/Heap

12. HashMap/HashSet

13. LinkedList

14. Binary Tree

15. Binary Search Tree

16. Sliding Window & Two pointer