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", "geeks", "for", "geeks" }
Output : geeks
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
#include <bits/stdc++.h>
using namespace std;
void printDuplicates(vector<string> words)
{
vector<string> duplicate;
sort(words.begin(), words.end());
for ( int i = 1; i < words.size(); i++) {
if (words[i - 1] == words[i]) {
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;
}
int main()
{
vector<string> words{ "welcome" , "to" , "geeks" , "for" ,
"geeks" , "to" , "geeks" };
printDuplicates(words);
return 0;
}
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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
#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;
}
int main()
{
vector<string>words{ "welcome" , "to" , "geeks" ,
"for" , "geeks" };
printDuplicates(words);
return 0;
}
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Output:
geeks
Last Updated :
25 Nov, 2020
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