CODEWITHSUNDEEP
javaarraysmethodsreplaceduplicates
user2750830
user2750830

Reputation: 17

Replacing a number in an array if duplicates are found

Make the user enter 5 integer values into the array in the main method. Pass array into a separate function. There, check for duplicated values in the array. If duplicates are found, eliminate the duplicate integer and replace it with -1. Print the processed array back in the main method.. i think i know how to replace the value with -1 but how do I return the array to the main back again. The code is:

 package methods;
import java.util.*;
public class remdup {
    public static void main (String[]args) {
    Scanner in = new Scanner (System.in);
    System.out.println("Enter 5 integers:  ");
    int [] x= new int [5];
    for (int i=0; i<5; i++) {
    x[i]=in.nextInt();
}
    check(x);
   // Insert method here 
}
    //Method check starts here...
    public static void check(int []y) {
      //  int pos = y[0];
        int len=y.length;
        int i=0;
        int j = i+1;
       for (i=0; i<len-1; i++) {
           for (j=i+1; j<len-1;j++ ) {
            if (y[i]==y[j]) {
                //how to replace numbers???
               y[i]=-1;
                System.out.println("Duplicate found");
            }
            }
        } 

    }
}

Upvotes: 0

Views: 6110

Answers (6)

Ashish Kathait
Ashish Kathait

Reputation: 216

Though this is a very old post I think there is an error in the accepted answer. We should be adding the replaced number back to the array. However in the accepted answer we are replacing it with -1 but we are never adding it back to SET. Below is my corrected solution :

    public static Set<Integer> check(int []y) {
        Set<Integer> foundNumbers = new HashSet<Integer>();
    
        for(int index = 0; index < y.length; index++) {
            if(foundNumbers.contains(y[index])){
                y[index] = -1;      
               
            } 
            
            foundNumbers.add(y[index]);
        }
         return foundNumbers;
        
    }

Upvotes: 0

Ruchira Gayan Ranaweera
Ruchira Gayan Ranaweera

Reputation: 35557

This will work for you. 

    public static void main(String[] args){
    Scanner in = new Scanner (System.in);
    System.out.println("Enter 5 integers:  ");
    Map<Integer,Integer> map=new HashMap<>();
    int [] x= new int [5];
    for (int i=0; i<5; i++) {
        int val=in.nextInt();
        x[i]=val;
        Integer iniVal=map.get(val);
        if(iniVal==null){
             iniVal=0;
        }
        map.put(val,iniVal+1);
    }
    int[] y=getNewArr(x,map);
    for (int i=0;i<y.length;i++){
        System.out.println(y[i]);
    }
}
public static int[] getNewArr(int[] x,Map<Integer,Integer> map){
    for(int i=0;i<x.length;i++){
        int numElement=map.get(x[i]);
        if(numElement!=1){
          for(int j=0;j<i;j++){
             if(x[i]==x[j]){
                    x[i]=-1;
             }
          }
        }
    }
     return x;
}

input array: {1,4,5,1,2}

Output array: {1,4,5,-1,2}

Upvotes: 0

SpringLearner
SpringLearner

Reputation: 13844

Change your whole like this way

   import java.util.*;
    public class test1 {
        public static void main (String[]args) {
        Scanner in = new Scanner (System.in);
        System.out.println("Enter 5 integers:  ");
        int [] x= new int [5];
        for (int i=0; i<5; i++) {
        x[i]=in.nextInt();
    }
        int z[]=check(x);
        for(int o=0;o<z.length;o++)
        {
            System.out.println(z[o]);
        }
       // Insert method here 
    }
        //Method check starts here...
        public static int[] check(int []y) {
          //  int pos = y[0];
            int len=y.length;
            int i=0;
            //int j = i+1;
           for (i=0; i<len; i++) {
               for(int j=0;j<i;j++)
               {
                if (y[i]==y[j]) {
                    //how to replace numbers???
                    y[i]=-1;
                   // System.out.println("Duplicate found");
                }
            } }
           for(int k=0;k<len;k++)
           {
               //System.out.println(y[k]);
           }
return y;
        }

}

Upvotes: 0

Marco Forberg
Marco Forberg

Reputation: 2644

use a Set to keep track of the numbers you already have. Iterate over your array and check if the set contains the number at your current position. if yes: replace it with -1. if no: add the number to the set...

public static void check(int []y) {
    Set<Integer> foundNumbers = new HashSet<Integer>();

    for(int index = 0; index < y.length; index++) {
        if(foundNumbers.contains(y[index]) {
            y[index] = -1;
        } else {
            foundNumbers.add(y[index]);
        }
    }
}

Upvotes: 3

npinti
npinti

Reputation: 52185

Since this is homework, I will not go into details however, if you look at your check function:

public static void check(int []y) {
      //  int pos = y[0];
        int len=y.length;
        int i=0;
        int j = i+1;
       for (i=0; i<len-1; i++) {
            if (y[i]==y[j]) {
                //how to replace numbers???
                System.out.println("Duplicate found");
            }
        } 

    }

You will notice that you are initially setting j to 1, but you are never updating its value. So in your for loop, you need to update the value of j at the end of each iteration.

You also need to include an extra loop, one which holds the current number and another one which checks the rest. Lastly, to overwrite the value you have, simply write to the array like so: y[i] = -1.

Upvotes: 0

Philipp Sander
Philipp Sander

Reputation: 10249

you replace number in the array like this:

y[i] = -1;

but your check function will not work this way.

Upvotes: 0

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