Find and print duplicate words in std::vector<string> using STL functions
Consider an array of string and find duplicate words in that array and print that duplicate words if exist.
Examples:
Input : { "welcome", "to", "Beginner", "for", "Beginner" } Output : Beginner Input : { "reduce", "reuse", "recycle", "reduce", "reuse", "recycle", " recycle" } Output : recycle reduce reuse Input : { "Go", "Green" } Output : No Duplicate words
Method 1 (Using Sorting)
1. Sort array of string.
2. compare adjacent word in array of string.
3. if two word are same then push that word in another vector string.
4. print the duplicate words if exist.
CPP
// CPP program to find duplicate word in a // vector<string> #include <bits/stdc++.h> using namespace std; void printDuplicates(vector<string> words) { vector<string> duplicate; // STL function to sort the array of string sort(words.begin(), words.end()); for ( int i = 1; i < words.size(); i++) { if (words[i - 1] == words[i]) { // STL function to push the duplicate // words in a new vector string if (duplicate.empty()) duplicate.push_back(words[i]); else if (words[i] != duplicate.back()) duplicate.push_back(words[i]); } } if (duplicate.size() == 0) cout << "No Duplicate words" << endl; else for ( int i = 0; i < duplicate.size(); i++) cout << duplicate[i] << endl; } // Driver code int main() { vector<string> words{ "welcome" , "to" , "Beginner" , "for" , "Beginner" , "to" , "Beginner" }; printDuplicates(words); return 0; } |
Output
Beginner to
Method 2 (Using Hashing)
1. Create an empty hash table.
2. One by one traverse words.
3. For every word check if already exists in the hash.
……..if (already exists in hash)
………….Print the word
……..Else
………….Insert the word in hash.
CPP
// CPP program to find duplicate word in a // vector<string> #include<bits/stdc++.h> using namespace std; void printDuplicates(vector<string> words) { unordered_set<string> s; bool dupFound = false ; for ( int i = 1; i<words.size(); i++) { if (s.find(words[i]) != s.end()) { cout << words[i] << endl; dupFound = true ; } else s.insert(words[i]); } if (dupFound == false ) cout << "No Duplicate words" << endl; } // Driver code int main() { vector<string>words{ "welcome" , "to" , "Beginner" , "for" , "Beginner" }; printDuplicates(words); return 0; } |
Output:
Beginner
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