Merge pull request #1454 from PuravUdayDesai/#1439-PuravUdayDesai

Added Boyer Moore Majority Vote Algorithm in Js

JavaScript/Algorithms/BoyerMooreAlgorithm.js

@@ -0,0 +1,98 @@
+    /*
+     *   An arrow function with 1 parameter and returns a value.
+     *   @param {Array} arrayOfCandidates contains a list of candidates
+     *   @return {number} majority candidate value selected by the algorithm
+     *   
+     *   This function determines the candidate who has the 
+     *   the majority number of votes, this algorithm was proposed by Boyer Moore's. 
+     */
+    const selectCandidate = (arrayOfCandidates) => {
+
+        var majorityVotes = 1; //contains the vote number of the candidate
+        var majorityCandidate = arrayOfCandidates[0]; //contains current majority candidate
+
+        for (var i = 1; i < arrayOfCandidates.length; i++) //Iterates through the list of candidates
+        {
+
+            /*
+             * checks whether the current candidate value is 
+             * same as of it's preceding one
+             */
+            if (majorityCandidate == arrayOfCandidates[i]) {
+                majorityVotes++;
+            } else {
+                majorityVotes--;
+            }
+
+            /*
+             * If majorityVotes deduct to 0 then a new candidate 
+             * is assigned and the value of majorityVotes reset to 1
+             */
+            if (majorityVotes <= 0) {
+                majorityVotes = 1; //Resetting value of majorityVotes
+                majorityCandidate = arrayOfCandidates[i]; //Assigning new candidate
+            }
+        }
+        return majorityCandidate; //Returns MajorityCandidate selected by the algorithm
+    }
+
+    /*
+     *  An arrow function with 2 parameters and returns a value
+     *  @param {Array} arrayOfCandidates contains a list of candidates
+     *  @param {number} selectedCandidate the selected candidate by the Boyer Moore's Algorithm
+     *  @return {boolean} verifies and returns that the given candidate is Majority Candidate or not
+     * 
+     * This function verifies that the given candidate selected is a valid candidate 
+     * and satisfies the need of having votes greater than 50% of the length of the list.
+     */
+    const validateSelectedCandidate = (arrayOfCandidates, selectedCandidate) => {
+
+        var countOfSelectedCandidate = 0; //counts number of seats earned of the candidate
+
+        //Iterates through the list of candidates
+        arrayOfCandidates.forEach(candidate => {
+
+            /*
+             *   If the selected candidate by the algorithm has the value equal
+             *   to the current element value than the countOfSelectedCandida
+             *   is incremented by 1
+             */
+            if (selectedCandidate == candidate) {
+                countOfSelectedCandidate++;
+            }
+        });
+        /*
+         *  Verifies that the total count of the candidate 
+         *  is greater than 50% of the total length of the list
+         * 
+         *  returning true signifies that the selected candidate is a legit candidate and has majority votes
+         *  returning false signifies that the selected candidate is not a legit candidate and no majority candidate is detected in the list
+         */
+        if (countOfSelectedCandidate > (arrayOfCandidates.length / 2)) {
+            return true;
+        }
+        return false;
+    };
+
+    /*
+     *  An arrow function with 1 parameter and no return value
+     *  @param {Array} listOfCandidates contains a list of candidates 
+     * 
+     *  This function acts as the main entry point for the execution flow
+     */
+    const main = (listOfCandidates) => {
+        var selectedCandidate = selectCandidate(listOfCandidates); //Fetches value of the selected candidate
+        var result = validateSelectedCandidate(listOfCandidates, selectedCandidate); //Passes the candidate for verification and gets the result
+        if (result) {
+            console.log(selectedCandidate + " Has The Majority Number Of Votes")
+        } else {
+            console.log("No Majority Candidate Detected")
+        }
+    }
+
+    //Declaration of list of candidates
+    var listOfCandidates = new Array(3, 3, 3, 3, 1, 1, 1, 3, 2);
+    //Calls main function for starting execution process
+    main(listOfCandidates);
+
+    //Output : 3 Has The Majority Number Of Votes

JavaScript/README.md

@@ -12,6 +12,7 @@
 ## Algorithms
 - [Russian Peasant Algorithm](Algorithms/RussianPeasant.js)
 - [Z Algorithm](Algorithms/ZAlgorithm.js)
+- [Boyer Moore's Majority Vote Algorithm](Algorithms/BoyerMooreAlgorithm.js)
 
 ## Data Structures