C++ Tutorial Index

C++ Tutorial C++ History C++ Installation C++ First Program C++ cin and cout C++ Data type C++ Variable C++ operator C++ Keywords

C++ Control Statements

C++ If C++ Nested if C++ If-else C++ If-else-if C++ Switch C++ Break C++ Continue C++ Goto C++ For loop C++ While loop C++ Do while loop

C++ Functions

C++ Call by Value C++ Call by Reference C++ Recursion Function C++ Inline function C++ Friend function

C++ Arrays

Single dimension array Two dimension array

C++ Strings

C++ Strings

C++ Inheritance

C++ Inheritance Single level Inheritance Multilevel Inheritance Multiple Inheritance Hierarchical Inheritance Hybrid Inheritance

C++ Polymorphism

C++ Polymorphism C++ Overloading C++ Overriding C++ Virtual Function

C++ Pointers

C++ Pointers C++ this pointer

C++ Exception Handling

C++ Exception Handling

C++ Constructors

C++ Constructors Default Constructor Parameterize Constructor Copy constructor Constructor Overloading Destructor

C++ File Handling

C++ File Handling C++ Writing to file C++ Reading file C++ Close file

Miscellaneous

C Vs C++ C++ Comments C++ Data Abstraction C++ Identifier C++ Memory Management C++ Storage Classes C++ Void Pointer C++ Array To Function C++ Expressions C++ Features C++ Interfaces C++ Encapsulation std::min in C++ External merge sort in C++ Remove duplicates from sorted array in C++ Precision of floating point numbers Using these functions floor(), ceil(), trunc(), round() and setprecision() in C++ C++ References C++ Friend Functions C++ Mutable keyword Unary Operators in C++ Initialize Array of objects with parameterized constructors in C++ Differences between #define & const in C/C++ C++ Program to Implement Shell Sort C++ Program to Implement Merge Sort Storage Classes in C Vector resize() in C++ Passing by Reference Vs. Passing by the pointer in C++ Free vs delete() in C++ goto statement in C and C++ C++ program to read string using cin.getline() C++ String Concatenation Heap Sort in C++ Swap numbers in C++ Input Iterators in C++ Fibonacci Series in C++ C ++ Program: Alphabet Triangle and Number Triangle C++ Program: Matrix Multiplication C++ Program to Print Fibonacci Triangle Stack in C++ Maps in C++ Queue in C++ C++ Bitset C++ Algorithms Priority Queue in C++ C++ Multimap C++ Deque Function Pointer in C++ Sizeof() Operators in C++ C++ array of Pointers free() Vs delete in C Timsort Implementation Using C++ CPP Templates C++ Aggregation C++ Enumeration C++ Math Functions C++ Object Class C++ Queue Initialize Vector in C++ Vector in C++ C++ STL Components Function overloading in C++ C++ Maximum Index Problem C++ find missing in the second array C++ Program to find the product array puzzle C++ Program To Find Largest Subarray With 0 Sum C++ Program To Move All Zeros To The End Of The Array C++ Program to find the element that occurs once C++ Program to find the largest number formed from an array Constructor Vs Destructor C++ Namespaces C++ OOPs Concept C++ Static C++ Structs C++ Try-Catch C++ User Defined Exceptions C++ Virtual Destructor C++ vs C# Malloc() and new in C++ Palindrome Number Program in C++ Snake Code in C++ Splitting a string in C++ Structure Vs Class in C++ Virtual Function Vs Pure Virtual Function C++ Bidirectional Iterators C++ Forward Iterators C++ Iterators C++ Output Iterators C++ Range-based For Loop Converting string into integer in C++ LCM Program in C++ Type conversion in C++ Add two numbers using the function in C++ Advantage and disadvantage friend function C++ Armstrong Number Program in C++ ATM machine program in C++ using functions Binary to Decimal in C++ Bit Manipulation in C++ C++ Constructor C++ Dijkstra Algorithm Using the Priority Queue C++ int into String C++ Signal Handling Decimal to Binary in C++ Decimal to Hexadecimal in C++ Decimal to Octal in C++ Factorial Program in C++ Function in C++ Hexadecimal to Decimal in C++ Octal to Decimal in C++ Reverse a Number in C++ Structure Vs Class in C++ C++ Forward Iterators C++ Output Iterators C++ Prime number program Char Array to String in C++ Constructor Overloading in C++ Default arguments in C++ Different Ways to Compare Strings in C++ Dynamic Binding in C++ Program to convert infix to postfix expression in C++ SET Data Structure in C++ Upcasting and Downcasting in C++ Reverse an Array in C++ Fast Input and Output in C++ Delete Operator in C++ Copy elision in C++ C++ Date and Time C++ Bitwise XOR Operator Array of sets in C++ Binary Operator Overloading in C++ Binary Search in C++ Implementing the sets without C++ STL containers Scope Resolution Operator in C++ Smart pointers in C++ Types of polymorphism in C++ Exception Handling in C++ vs Java Const Keyword in C++ Type Casting in C++ Static keyword in C++ vs Java Inheritance in C++ vs Java How to concatenate two strings in C++ Programs to Print Pyramid Patterns in C++ swap() function in C++ Structure of C++ Program Stringstream in C++ and its applications rand() and srand() in C / C++ C++ Ternary Operator C++ Scope of Variables While Loop Examples in C++ Star pattern in C++ using For Loops For Loop Examples in C++ Do-While Loop Examples in C++ Top 5 IDEs for C++ That You Should Try Once Assertions in C/C++ C++ Convert Int to String Continue in C++ While loop Diamond Pattern in C++ using For Loop How to Reverse a String in C++ using Do-While Loop How to Reverse a String in C++ using For Loop How to Reverse a String in C++ using While Loop Infinite loop in C++ Loops in C++ Returning Multiple Values from a Function using Tuple and Pair in C++ wcscpy(), wcslen(), wcscmp() Functions in C++

Remove duplicates from sorted array in C++

Remove duplicates from the sorted array in C++.

This same process, due to a sorted array, is to erase the redundant components from the array.

Examples:

Input  : arr[] = {2, 2, 2, 2, 2}
Output : arr[] = {2}
         new size = 1
Input  : arr[] = {1, 2, 2, 3, 4, 4, 4, 5, 5}
Output : arr[] = {1, 2, 3, 4, 5}
         new size = 5

Method 1: (Using extra space)

  • Generate an auxiliary temp[] array for storing different aspects.
  • Traverse the input array and duplicate different aspects from arr[] to temp[] one by one. Keep records of counting different aspects, as well. Let the count be j.
  • Copy j elements to arr[] from temp, and return j.

Example:

// Simple C++ program to remove duplicates
#include<iostream>
using namespace std;
/* Removes duplicate components
The above function will return the prototype model size
Display.*/
int removeDuplicates(int array[], int p)
{
          // Return, if array is empty
          // or contains a single element
          if (p==0 || p==1)
                   return p;
          int temp[p];
          // Start traversing elements
          int k = 0;
          for (int i=0; i<p-1; i++)
                   // If current element is not equal
                   // to next element then store that
                   // current element
                   if (array[i] != array[i+1])
                             temp[k++] = array[i];
          // Store the last element as whether
          // it is unique or repeated, it hasn't
          // stored previously
          temp[k++] = array[p-1];
          // Modify original array
          for (int i=0; i<k; i++)
                   array[i] = temp[i];
          return k;
}
// Driver code
int main()
{
          int array[] = {1, 2, 2, 3, 4, 4, 4, 5, 5, 6, 7, 7, 8, 8, 8, 9, 9 ,10, 11};
          int p = sizeof(array) / sizeof(array[0]);
          // removeDuplicates() returns new size of
          // array.
          p = removeDuplicates(array, p);
          // Print updated array
          for (int i=0; i<p; i++)
          cout << array[i] << " ";
          return 0;
}

Output:

Remove duplicates from sorted array in CPP

Time Complexity: O(n)
Auxiliary Space: O(n)

Method 2: (Constant extra space)

Just hold a totally separate index for the same array as kept in Method 1 for the different array.

Example:

/* C++ program to remove duplicates in-place*/
#include<iostream>
using namespace std;
int removeDuplicates(int array[], int t)
{
          if (t==0 || t==1)
                   return t;
          // To store index of next unique element
          int k = 0;
          for (int i=0; i < t-1; i++)
                   if (array[i] != array[i+1])
                             array[k++] = array[i];
          array[k++] = array[t-1];
          return k;
}
// Driver code
int main()
{
          int array[] = {1, 1, 1, 2, 2, 2, 3, 4, 4, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9};
          int t = sizeof(array) / sizeof(array[0]);
          // removeDuplicates() returns new size of
          // array.
          t = removeDuplicates(array, t);
          for (int i=0; i<t; i++)
                   cout << array[i] << " ";
          return 0;
}

Output:

Remove duplicates from sorted array in CPP

Time Complexity: O(n)
Auxiliary Space: O(1)



ADVERTISEMENT
ADVERTISEMENT