Conditionals

Notes

Conditionals are expressions that evaluate to either true or false or simply statements which run under certain conditions.
An operator in a programming language is a symbol that is used to perform operation on data. It acts as connector and indicate type of operation being carried out.
Operator are broadly classified into 3 types: Unary, Binary, Ternary.
If statement: The simplest type of conditional statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.

Syntax
  if(condition) 
  {
      // Statements to execute if
      // condition is true
  }

Else statement: We can use the else statement with if statement to execute a block of code when the condition is false.

Syntax
  if (condition)
  {
      // Executes this block if
      // condition is true
  }
  else
  {
      // Executes this block if
      // condition is false
  }

Nested if : A nested if is an if statement that is the target of another if statement. Nested if statements means an if statement inside another if statement.

Syntax
  if (condition1) 
  {
      // Executes when condition1 is true
      if (condition2) 
      {
        // Executes when condition2 is true
      }
  }

Else if statement: This is used when we want to deal with more than 2 outcomes of a condition. The execution takes place in top-down fashion i.e if 1st condition is false it moves down to the next until a true condition is found after which it stops checking and executes the statement of that condition. It is also known as if-else if ladder.

Syntax
  if (condition)
      statement;
  else if (condition)
      statement;
  else
      statement;

The break statement: Used to terminate a flow of operations if a certain condition is met.(i.e to exit from a loop)

Syntax
  break;

The continue statement: Used to skip the current operation and proceed to next if a certain condition is met.

Syntax
  continue;

The goto statement: Also referred to as unconditional jump statement can be used to jump from one point to another within a function.

Syntax
  goto label;
  .
  .
  .
  label:

The return statement: Returns the flow of the execution to the function from where it is called.

Syntax
  return[expression];

The Switch-Case: Switch case statements are a substitute for long if statements that compare a variable to several integral values. It provides an easy way to dispatch execution to different parts of code based on the value of the expression.

Syntax
  switch (n)
  {
      case 1: // code to be executed if n = 1;
          break;
      case 2: // code to be executed if n = 2;
          break;
      default: // code to be executed if n doesn't match any cases
  }

Useful Links

🔗 Operators 🔗Conditional or Ternary Operator 🔗 Decision Making 🔗 Switch Statement

Questions

Write a program to calculate the total salary of a person. The user has to enter the basic salary (an integer) and the grade (an uppercase character), and depending upon which the total salary is calculated as

totalSalary = basic + hra + da + allow – pf
where : 
  hra   = 20% of basic
  da    = 50% of basic
  allow = 1700 if grade = ‘A’
  allow = 1500 if grade = ‘B’
  allow = 1300 if grade = ‘C’ or any other character
  pf    = 11% of basic.

Example :
    Input 1:
    10000 A
    Output 1:
    17600
    Input 2:
    4567 B
    Output 2:
    8761

Explanation: 
We have been given the basic salary as Rs. 4567. We need to calculate the hra, da and pf. Now when we calculate each of the, it turns out to be:
hra =  20% of Rs. 4567 = Rs. 913.4
da = 50% od Rs. 4567 = Rs. 2283.5
pf = 11% of Rs. 4567 = Rs. 502.37
Since, the grade is 'B', we take allowance as Rs. 1500.
On substituting these values to the formula of totalSalary, we get Rs. 8761.53 and now taking its integer value, we get 8761.

Write a program where we enter a date in dd/mm/yy format and print it in words using conditional statements.
```
Example :
  Input:
  22 
  06 
  2021
  Output:
  June 22 2021 
```

Write a program to calculate and print the Water bill of a given customer. The customer id., name and water consumed by the user in litre should be taken from the user and display the total amount to pay to the customer.

The charges are as follows: 
    Unit Charge/litre 
    upto 199 @3 
    200 and above but less than 400 @3.35 
    400 and above but less than 600 @4.80 
    600 and above @5.10 
    If bill exceeds Rs. 1250 then a surcharge of 15% will be charged.

Format :
  Input Format:
    Input Customer ID 
    Input the name of the customer 
    Input the litres consumed by the customer 
  Output Format:
    10001
    James
    800
    4691

Example :
  Input :
  10001
  James
  800
  Output:
  10001
  James
  800
  4691

Write a program to accept a coordinate point in an XY coordinate system and determine in which quadrant the coordinate point lies.

“Quadrant 1” if +x,+y
  “Quadrant 2” if -x,+y
  “Quadrant 3” if -x,-y
  “Quadrant 4” if +x,-y
  “X axis” if x,0
  “Y axis” if 0,y
  “Origin” if 0,0.

Format :
  Input Format:
    The only line of input contains two integers separated by a single space.
  Output Format:
    The only line of the output prints the Position of the point in the coordinate system.

Example :
  Input 1:
    5 100
  Output 1:
    Quadrant 1
  Input 2:
    0 -80
  Output 2:
    Y axis

Explanation: 
  Since x is 0 and the point lies in y-axis

Write a program to create a simple calculator which can perform basic arithmetic operations like addition, subtraction, multiplication or division depending upon the user input.

Format :
  Input Format:
    First 2 lines contain the 2 integwld be performed on.
    Next line would contain the operator in the character format
  Output Format:
    Return the answer

Example :
  Input 1:
    6
    2
    +
  Output 1:
    8
  Input 2:
    7
    8
    * 
  Output 2:
    56

Back

Looping

Notes

A loop statement allows us to execute a statement or group of statements multiple times.
An entry control loop checks the condition at the time of entry and if the condition or expression (statement that has value) becomes true then control transfers into the body of the loop. Example: for loop and while loop
An exit control loop checks the condition for exit and if given condition for exit evaluate to true, control will exit from the loop body or else control will enter again into the loop. Example: Do while loop
A while loop statement repeatedly executes a target statement as long as a given condition is true.

Syntax
  initialization expression;
  while (test_expression)
  {
      // statements
    
    update_expression;
  }

A for loop is a repetition control structure that allows you to efficiently write a loop that needs to execute a specific number of times.

Syntax
  for (initialization expr; test expr; update expr)
  {    
    // body of the loop
    // statements we want to execute
  }

A do-while loop is similar to a while loop, except the fact that it is guaranteed to execute at least one time. It checks its condition at the bottom of the loop.

Syntax
  initialization expression;
  do
  {
  // statements

  update_expression;
  } while (test_expression);

A loop can be used inside of another loop. This is known as nesting. Nested for loops are most commonly used in problem solving.

Syntax for Nested For loop:
  for ( initialization; condition; increment ) {

    for ( initialization; condition; increment ) {
        
        // statement of inside loop
    }

    // statement of outer loop
  }

Syntax for Nested while loop:
  while(condition) {

    while(condition) {
      
      // statement of inside loop
    }

    // statement of outer loop
  }

Syntax for Nested do-while loop:
  do{

    do{
      
      // statement of inside loop
    }while(condition);

    // statement of outer loop
  }while(condition);

Useful Links

🔗 loops in C++ Tutorial 🔗 While loop 🔗 For loop 🔗 do-while loop 🔗 Nested Loops

Questions

Given a number N, find its square root without using inbuilt functions. You need to find and print only the integral part of the square root of N.
```
Example :
  Input : 10
  Output : 3
```
Solution
💡 C++ 💡 Java 💡 Python

Print the following pattern for the given number of rows.

Example :
  Input :
      N = 8
  Output :
      H
      GH
      FGH
      EFGH
      DEFGH
      CDEFGH
      BCDEFGH
      ABCDEFGH

Solution

💡 C++ 💡 Java 💡 Python

Print the following pattern for the given number of rows.

Example :
  Input :
      N = 5
  Output :
      ••*
      •***
      *****                          
      •***           
      ••*
 Note : The dots represent spaces and N is always odd.

Solution

💡 C++ 💡 Java 💡 Python

Write a program to print all the prime numbers that fall between 2 numbers given as input by the user.
```
Example :
  Input :
      a = 10
      b = 20  
  Output :
      11 13 17 19
```
Solution
💡 C++ 💡 Java 💡 Python

Take input a stream of n integer elements, find the second largest element present.
The given elements can contain duplicate elements as well. If only 0 or 1 element is given, the second largest should be INT_MIN ( -2³¹ ).

Format :
  Input Format :
    Line 1 : Total number of elements (n)
    Line 2 : N elements (separated by space)
  Output Format :
    Return the answer

Example :
  Input 1 :
      4
      3 9 0 9    
  Output 1 :
      3
  Input 2 :
      2
      4 4    
  Output 2 :
      -2147483648
  Explanation :
      Since both the elements are equal here, hence second largest element is INT_MIN i.e. ( -2³¹ )

Solution

💡 C++ 💡 Java 💡 Python

Back

Arrays

Notes

An array is a collection of similar data items stored at contiguous memory locations and elements can be accessed randomly using indices of an array.

Syntax to declare an array :
  dataType arrayName[arraySize];
Syntax to initialize an array :
  dataType arrayName[arraySize] = {d1, d2, d3...., dn};

Array elements are accessed by using an integer index. Array index starts with 0 and goes till size of array -1.
One-dimensional array is a group of elements having the same datatype and are stored in a linear form.
Multidimensional arrays in simple words as array of arrays.
Two-dimensional arrays can be referred to as arr[i][j] wherein i is considered to be the row number and j is considered to be column number. In this data is stored in rows and columns.

Syntax of 1-D array:
  data_type array_name[size];
Syntax of 2-D array :
  data_type array_name[row][columns];
Syntax of 3-D array:
  data_type array_name[size1][size2][size3];

Sorting means arranging the data in a particular fashion, which can be increasing or decreasing.
Searching is the process of finding the required data in the array.
There are two techniques of searching elements in array:
Sequential Search : We compare targeted element with each element of the array. If the element is found then its position is displayed.
Binary Search : Finding the required element in a sorted array by repeatedly halving the array and searching in the half.
Vector are same as dynamic arrays with the ability to resize itself automatically when an element is inserted or deleted, with their storage being handled automatically by the container.
Vector elements are placed in contiguous storage so that they can be accessed and traversed using iterators. In vectors, data is inserted at the end.

Syntax to declare an vector :
    vector<data_type> vector_name(size);

Useful Links

🔗 Arrays 🔗 Multidimensional Arrays 🔗 Vector

Questions

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
You may assume that each input would have exactly one solution, and you may not use the same element twice. You can return the answer in any order.

Example :
  Input 1 :
      nums = [2,7,11,15], target = 9   
  Output 1 :
      [0,1]
  Explanation :
      Because nums[0] + nums[1] == 9, we return [0, 1].
  Input 2 :
      nums = [3,2,4], target = 6    
  Output 2 :
      [1,2]

Constraints :
  • 2 <= nums.length <= 104
  • -109 <= nums[i] <= 109
  • -109 <= target <= 109
  • Only one valid answer exists.

Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that:.

• 0
              <= a, b, c, d < n

• a, b, c, and d are distinct.
• nums[a] + nums[b] + nums[c] + nums[d] == targe
You can return the answer in any order.

Example :
  Input 1 :
      nums = [1,0,-1,0,-2,2], target = 0   
  Output 1 :
      [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]
  Input 2 :
      nums = [2,2,2,2,2], target = 8    
  Output 2 :
    [[2,2,2,2]]

Constraints :
  • 1 <= nums.length <= 200
  • -109 <= nums[i] <= 109
  • -109 <= target <= 109

Given an array of integers nums sorted in ascending order, find the starting and ending position of a given target value.
If target is not found in the array, return [-1, -1]. You must write an algorithm with O(log n) runtime complexity.

Example :
  Input 1 :
      nums = [5,7,7,8,8,10], target = 8  
  Output 1 :
      [3,4]
  Input 2 :
      nums = [5,7,7,8,8,10], target = 6    
  Output 2 :
      [-1,-1]

Constraints :
  • 0 <= nums.length <= 105
  • -109 <= nums[i] <= 109
  • nums is a non-decreasing array.
  • -109 <= target <= 109

Given a triangle array, return the minimum path sum from top to bottom.
For each step, you may move to an adjacent number of the row below. More formally, if you are on index i on the current row, you may move to either index i or index i + 1 on the next row.

Example :
  Input 1 :
      triangle = [[2],[3,4],[6,5,7],[4,1,8,3]]   
  Output 1 :
      11
  Explanation :
      The triangle looks like:
         2
        3 4
       6 5 7
      4 1 8 3
      The minimum path sum from top to bottom is 2 + 3 + 5 + 1 = 11
  Input 2 :
      triangle = [[-10]]
  Output 2 :
      -10

Constraints :
  • 1 <= triangle.length <= 200
  • triangle[0].length == 1
  • triangle[i].length == triangle[i - 1].length + 1
  • -104 <= triangle[i][j] <= 10⁴

Given an array of integers arr, sort the array by performing a series of pancake flips.
In one pancake flip we do the following steps:

• Choose an integer k where 1
              <= k <=arr.length.

• Reverse the sub-array arr[0...k-1] (0-indexed)
For example, if arr = [3,2,1,4] and we performed a pancake flip choosing k = 3, we reverse the sub-array [3,2,1], so arr = [1,2,3,4] after the pancake flip at k = 3. Return an array of the k-values corresponding to a sequence of pancake flips that sort arr. Any valid answer that sorts the array within 10 * arr.length flips will be judged as correct.

Example :
  Input 1 :
      arr = [3,2,4,1]   
  Output 1 :
      [4,2,4,3]
  Explanation :
  We perform 4 pancake flips, with k values 4, 2, 4, and 3.
    Starting state: arr = [3, 2, 4, 1]
    After 1st flip (k = 4): arr = [1, 4, 2, 3]
    After 2nd flip (k = 2): arr = [4, 1, 2, 3]
    After 3rd flip (k = 4): arr = [3, 2, 1, 4]
    After 4th flip (k = 3): arr = [1, 2, 3, 4], which is sorted.
  Input 2 :
      arr = [1,2,3]    
  Output 2 :
      []
  Explanation :
      The input is already sorted, so there is no need to flip anything.
      Note that other answers, such as [3, 3], would also be accepted.

Constraints :
  • 1 <= arr.length <= 100
  • 1 <= arr[i] <= arr.length
  • All integers in arr are unique

Back

Strings

Notes

A string variable contains a collection of characters surrounded by double quotes.

Syntax
     string string_name = "data";
Example
    string x = "Hello World";

String Concatenation : The + operator can be used between strings to add them together to make a new string. Or you can also concatenate strings with the append() function.

Example
    string x = "Hello ";
    string y = "World";
    string a = x + y;   // Hello World
    string b = x.append(y); // Hello World

String length : To get the length of a string, use the length() or size() function

Syntax
    string_name.length();
    string_name.size();
Example
    string x = "Hello World";
    cout << x.length();   // 11
    cout << x.size();   // 11

Access String : You can access the characters in a string by referring to its index number inside square brackets [].
Note: String indexes start with 0: [0] is the first character. [1] is the second character, etc.
User Input Strings : The getline() function to read a line of text. It takes cin as the first parameter, and the string variable as second.

Syntax
    getline (cin, string_name);

Useful Links

🔗 Strings 🔗 C++ Strings 🔗 Python Strings

Questions

A string is considered to be valid if all characters of the string appear the same number of times. It is also valid if he can remove just 1character at 1 index in the string, and the remaining characters will occur the same number of times. Given a string, determine if it is valid. If so, return YES, otherwise return NO.

Example :
  Input 1 :
      aabbcd  
  Output 1 :
      NO
  Explanation 1 :
      Given s=”aabbcd” , we would need to remove two characters, both c and d->aabb or a and b->abcd, to make it valid. We are limited to removing only one character, so given string is invalid.
  Input 2 :
      abcdefghhgfedecba
  Output 2 :
      YES
  Explanation 2 :
      All characters occur twice except for which occurs times. We can delete one instance of to have a valid string.

There is a sequence of words in CamelCase as a string of letters, having the following properties:
• It is a concatenation of one or more words consisting of English letters.
• All letters in the first word are lowercase.
• For each of the subsequent words, the first letter is uppercase and the rest of the letters are lowercase.
Given a string s, determine the number of words in s.
```
Example :
  Input :
      saveChangesInTheEditor
  Output :
      5
  Explanation :
      String  contains five words:
        save
        Changes
        In
        The
        Editor
```
Without using inbuilt library functions or recursion, write a program to determine whether a string entered by the user is palindrome or not for T test cases.
(USE LOOPING)
```
Example :
  Input 1 :
      abcdbca
  Output 1 :
      YES
  Input 2 :
      aabb
  Output 2 :
      NO
```

You are given a sentence s and an integer k. You want to truncate s such that it contains only the first k words. Return s after truncating it.
A sentence is a list of words that are separated by a single space with no leading or trailing spaces. Each of the words consists of only uppercase and lowercase English letters (no punctuation).

Example :
  Input :
      s = "Hello how are you Contestant", k = 4
  Output :
      "Hello how are you"
  Explanation :
      The words in s are ["Hello", "how" "are", "you", "Contestant"].
      The first 4 words are ["Hello", "how", "are", "you"].
      Hence, you should return "Hello how are you".

Constraints :
  • 1 <= s.length <= 500
  • k is in the range [1, the number of words in s].
  • s consist of only lowercase and uppercase English letters and spaces.
  • The words in s are separated by a single space.
  • There are no leading or trailing spaces.

Input a string from the user and change each of its substrings that spells "party" to "pawri". Find the resulting string
The first line of the input contains a single integer T denoting the number of test cases. The first and only line of each test case contains a single string S.

Example :
  Input :
      3
      part
      partypartiparty
      yemaihuyemericarhaiauryahapartyhorahihai
  Output 1 :
      part
      pawripartipawri
      yemaihuyemericarhaiauryahapawrihorahihai
Explanation :
    Case 1: 
      There is no substring "party" in the original string.
    Case 2: 
      The original string has 2 substrings "party".
    Case 3: 
      There is only a single substring "party" in the original string.

Back

CODE GENESIS

TOPICS

Conditionals

Notes

Useful Links

Questions

Looping

Notes

Useful Links

Questions

Solution

Solution

Solution

Solution

Solution

Arrays

Notes

Useful Links

Questions

Strings

Notes

Useful Links

Questions

Bit manipulation

Notes

Useful Links

Questions

Functions

Notes

Useful Links

Questions

Structures/classes

Notes

Useful Links

Questions

Basic Recursion

Notes

Useful Links

Questions