Find winner of an election where votes are represented as candidate names

25 May, 2022
Given an array of names of candidates in an election. A candidate’s name in the array represents a vote cast on the candidate. Print the name of candidates who received the maximum vote. If there is a tie, print a lexicographically smaller name.
Examples: 
Input :  votes[] = {"john", "johnny", "jackie", 
                    "johnny", "john", "jackie", 
                    "jamie", "jamie", "john",
                    "johnny", "jamie", "johnny", 
                    "john"};
Output : John
We have four Candidates with name as 'John', 
'Johnny', 'jamie', 'jackie'. The candidates
John and Johny get maximum votes. Since John
is alphabetically smaller, we print it.
A simple solution is to run two loops and count the occurrences of every word. The time complexity of this solution is O(n * n * MAX_WORD_LEN).
An efficient solution is to use Hashing. We insert all votes in a hash map and keep track of counts of different names. Finally, we traverse the map and print the person with the maximum votes.
C++
Java
Python3
C#
Javascript
// C++++ program to find winner in an election.#include "bits/stdc++.h"using namespace std;     /* We have four Candidates with name as 'John',      'Johnny', 'jamie', 'jackie'.       The votes in String array are as per the       votes casted. Print the name of candidates       received Max vote. */    void findWinner(vector<string>& votes)    {                 // Insert all votes in a hashmap        unordered_map<string,int> mapObj ;        for (auto& str : votes)        {            mapObj[str]++;        }          // Traverse through map to find the candidate        // with maximum votes.        int maxValueInMap = 0;        string winner;        for (auto& entry : mapObj)        {            string key  = entry.first;            int val = entry.second;            if (val > maxValueInMap)            {                maxValueInMap = val;                winner = key;            }              // If there is a tie, pick lexicographically            // smaller.            else if (val == maxValueInMap &&                winner>key)                winner = key;        }        cout << winner << endl;    }      // Driver code    int main()    {       vector<string> votes = { "john", "johnny", "jackie",                         "johnny", "john", "jackie",                         "jamie", "jamie", "john",                         "johnny", "jamie", "johnny",                         "john" };         findWinner(votes);       return 0;    }    
// Java program to find winner in an election.import java.util.*; public class ElectoralVotingBallot{    /* We have four Candidates with name as 'John',      'Johnny', 'jamie', 'jackie'.       The votes in String array are as per the       votes casted. Print the name of candidates       received Max vote. */    public static void findWinner(String votes[])    {        // Insert all votes in a hashmap        Map<String,Integer> map =                    new HashMap<String, Integer>();        for (String str : votes)        {            if (map.keySet().contains(str))                map.put(str, map.get(str) + 1);            else                map.put(str, 1);        }         // Traverse through map to find the candidate        // with maximum votes.        int maxValueInMap = 0;        String winner = "";        for (Map.Entry<String,Integer> entry : map.entrySet())        {            String key  = entry.getKey();            Integer val = entry.getValue();            if (val > maxValueInMap)            {                maxValueInMap = val;                winner = key;            }             // If there is a tie, pick lexicographically            // smaller.            else if (val == maxValueInMap &&                winner.compareTo(key) > 0)                winner = key;        }        System.out.println(winner);    }     // Driver code    public static void main(String[] args)    {       String[] votes = { "john", "johnny", "jackie",                         "johnny", "john", "jackie",                         "jamie", "jamie", "john",                         "johnny", "jamie", "johnny",                         "john" };        findWinner(votes);    }}
# Python3 program to find winner in an election.from collections import defaultdict ''' We have four Candidates with name as 'John','Johnny', 'jamie', 'jackie'.The votes in String array are as per thevotes casted. Print the name of candidatesreceived Max vote. '''def findWinner(votes):     # Insert all votes in a hashmap    mapObj = defaultdict(int)         for st in votes:        mapObj[st] += 1     # Traverse through map to find the    # candidate with maximum votes.    maxValueInMap = 0    winner = ""         for entry in mapObj:        key = entry        val = mapObj[entry]                 if (val > maxValueInMap):            maxValueInMap = val            winner = key         # If there is a tie, pick lexicographically        # smaller.        else if (val == maxValueInMap and              winner > key):            winner = key     print(winner) # Driver codeif __name__ == "__main__":     votes = [ "john", "johnny", "jackie",              "johnny", "john", "jackie",              "jamie", "jamie", "john",              "johnny", "jamie", "johnny",              "john" ]     findWinner(votes) # This code is contributed by ukasp
// C# program to find winner in an election.using System;using System.Collections.Generic; public class ElectoralVotingBallot{    /* We have four Candidates with name as 'John',    'Johnny', 'jamie', 'jackie'.    The votes in String array are as per the    votes casted. Print the name of candidates    received Max vote. */    public static void findWinner(String []votes)    {        // Insert all votes in a hashmap        Dictionary<String,int> map =                    new Dictionary<String, int>();        foreach (String str in votes)        {            if (map.ContainsKey(str))                map[str] = map[str] + 1;            else                map.Add(str, 1);        }         // Traverse through map to find the candidate        // with maximum votes.        int maxValueInMap = 0;        String winner = "";        foreach(KeyValuePair<String, int> entry in map)        {            String key = entry.Key;            int val = entry.Value;            if (val > maxValueInMap)            {                maxValueInMap = val;                winner = key;            }             // If there is a tie, pick lexicographically            // smaller.            else if (val == maxValueInMap &&                winner.CompareTo(key) > 0)                winner = key;        }        Console.WriteLine(winner);    }     // Driver code    public static void Main(String[] args)    {        String[] votes = { "john", "johnny", "jackie",                            "johnny", "john", "jackie",                            "jamie", "jamie", "john",                            "johnny", "jamie", "johnny",                            "john" };             findWinner(votes);    }} // This code is contributed by PrinciRaj1992
<script>// Javascript program to find winner in an election.         /* We have four Candidates with name as 'John',      'Johnny', 'jamie', 'jackie'.       The votes in String array are as per the       votes casted. Print the name of candidates       received Max vote. */    function findWinner(votes)    {        let map = new Map();        for(let i=0;i<votes.length;i++)        {            if(map.has(votes[i]))            {                map.set(votes[i], map.get(votes[i]) + 1);            }                         else                map.set(votes[i], 1);        }                 // Traverse through map to find the candidate        // with maximum votes.        let maxValueInMap = 0;        let winner = "";        for (let [key, value] of map.entries())        {            let Key  = key;            let val = value;            if (val > maxValueInMap)            {                maxValueInMap = val;                winner = key;            }              // If there is a tie, pick lexicographically            // smaller.            else if (val == maxValueInMap &&                winner>Key)                winner = Key;        }        document.write(winner);                         }         // Driver code    let votes=["john", "johnny", "jackie",                         "johnny", "john", "jackie",                         "jamie", "jamie", "john",                         "johnny", "jamie", "johnny",                         "john"];    findWinner(votes);    // This code is contributed by rag2127</script>
Output: 
John
Time Complexity: O(n)), where n is the total number of votes.
Auxiliary Space: O(n), since unordered_map data structure is used.
Another efficient solution is to use Trie. Please refer most frequent word in an array of strings.This article is contributed by Ishfaq Ramzan Nagoo. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. 
Ankit Verma 10
princiraj1992
ukasp
rag2127
aadityamp01
surinderdawra388
shivamanandrj9
Adobe
Java-HashMap
Microsoft
Hash
Strings
Microsoft
Adobe
Hash
Strings
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