CODEWITHSUNDEEP
c++arrays
Elias
Elias

Reputation: 11

How to find if there are ANY duplicate elements in Array? C++

I am trying to read in a wordlist of 50.000 words i have and sort out all words with duplicate letters. I have already managed to select a random word, convert it to chars in an array, but how do i search that array for duplicates?

Upvotes: 0

Views: 619

Answers (4)

user10691264
user10691264

Reputation:

I guess that you have an array of char pointers because of saying "convert it to chars in an array" so code would be like:

#include <iostream>

typedef const char* str;
str array [] = {"Hello", "how", "are", "you"};

bool isDuplicated (str word, str* array, int dimension);

int main() {

    int length = sizeof(array) / sizeof (char);
    str word = "Hello";
    std::cout << "The word " << word << " is duplicated: " << isDuplicated (word, array, length) << std::endl;
    std::cin.get();
}

bool isDuplicated(str word, str* array, int dimension) {
    bool duplicated = false;
    for(int i = 0; i < dimension; i ++) {
        if(array[i] == word) {
            duplicated = true;
            break;
        }
    }
    return duplicated;
}

Upvotes: 0

darune
darune

Reputation: 11146

You asked: select a random word, convert it to chars in an array, but how do i search that array for duplicates?

Using boost, this may be boiled down to:

const bool hasDuplicates = boost::size(letters) != boost::size(boost::unique(letters));

Upvotes: 0

code_cody97
code_cody97

Reputation: 100

You can also find duplicate words using hashing..

  • 1.first create hash table.

  • 2.one by one traverse words.

  • 3.for every word check if it already exists or not..if it is already present print word otherwise insert it into hash.

you can use unordered_set<string> s for hashing.

void printDup(vector<string> words) 
{ 
    unordered_set<string> s; 
    bool f = false; 
    for(int i = 1; i<words.size(); i++) 
    { 
        if (s.find(words[i]) != s.end()) 
        { 
            cout << words[i] << endl; 
            f = true; 
        } 
        else
            s.insert(words[i]); 
    } 
    if(f == false) 
        cout << "No Duplicate words" << endl; 
}

Upvotes: 0

bolov
bolov

Reputation: 75924

std::adjacent_find is your friend:

template< class ForwardIt >
ForwardIt adjacent_find( ForwardIt first, ForwardIt last );

Searches the range [first, last) for two consecutive identical elements.

Return value

an iterator to the first of the first pair of identical elements [...] If no such elements are found, last is returned

First sort the array, then do adjacent_find on it and check if it returns last or not.

Upvotes: 3

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