Java 2D Array logic implementation

Question

I got a question today and tried but doesn't found an relevent solution. The question is:

Suppose we have a 2D array containing the name of city and total number of products. The name of city could repeat in the list.

Now what we have to do is

1. Count the number of product sold in one city and save them in another 2d array having unique city name and total number of products sold.
2. Print the second city having highest products sold.

A sample list could be for consideration is:

private static String[][] arr = new String[][]{
        {"New Delhi", "5000"},
        {"Chennai", "4300"},
        {"Goa", "2940"},
        {"New Delhi", "2003"},
        {"Kolkata", "8904"},
        {"Kerala", "8972"},
        {"New Delhi", "8922"},
        {"Chennai", "8217"},
        {"New Delhi", "2462"},
        {"Kolkata", "5564"},
        {"Kerala", "9934"},
        {"New Delhi", "100"},
        {"Kolkata", "892"},
        {"Kerala", "9406"},
        {"New Delhi", "2003"},
        {"Chennai", "1049"}
    };

Note: I already tried this question with Map Interface. Only looking for solution with Multidimensional Array

Answer 1

Finally done that using 2d array and my code is

import java.util.Arrays;

/**
 *
 * @author Chirag
 */
public class Sampleh {

    private static final String[][] $DATA = new String[][]{
        {"New Delhi", "5000"},
        {"Chennai", "4300"},
        {"Goa", "2940"},
        {"New Delhi", "2003"},
        {"Kolkata", "8904"},
        {"Kerala", "8972"},
        {"New Delhi", "8922"},
        {"Chennai", "8217"},
        {"New Delhi", "2462"},
        {"Kolkata", "5564"},
        {"Kerala", "9934"},
        {"New Delhi", "100"},
        {"Kolkata", "892"},
        {"Kerala", "9406"},
        {"New Delhi", "2003"},
        {"Chennai", "1049"}
    };

    private static String[][] $result = new String[50][2];

    private static void action1() {
        outer:
        for (int i = 0; i < $DATA.length; i++) {
            String curCity = $DATA[i][0];
            Integer curProd = Integer.valueOf($DATA[i][1]);
            for (String[] city : $result) {
                if (city[0] == null) {
                    //for this loop
                    continue;
                }
                if (city[0].equals(curCity)) {
                    //for outer loop;
                    continue outer;
                }
            }
            for (int k = i; k < $DATA.length; k++) {
                if ($DATA[k][0].equals(curCity)) {
                    String n = $DATA[k][1];
                    if (n == null) {
                        n = "0";
                    }
                    curProd += Integer.valueOf(n);
                }
            }
            $result[i][0] = curCity;
            $result[i][1] = "" + curProd;
        }
        {
            //this code removes nulls from result array
            String[][] temp; //a temparory 2d array
            int counter = 0; //counts the num of values excluding nulls
            for (String[] res : $result) {
                if (res[0] == null) {
                    continue;
                }
                ++counter;
            }
            temp = new String[counter][2]; //redefine the temporary 2d array with size of values
            counter = 0;
            for (String[] res : $result) {
                if (res[0] == null) {
                    continue;
                }
                temp[counter][0] = res[0];
                temp[counter][1] = res[1];
                counter++;
            }
            $result = temp; //copy all values from temporary array to global result array
        }

        //prints the final array which is not sorted
        for (String[] r : $result) {
            System.out.println("City " + r[0] + " have " + r[1] + " products");
        }
    }

    private static void action2() {
        String[] cities = new String[$result.length];
        int[] products = new int[$result.length];
        int[] prodCopy = new int[$result.length];

        for (int i = 0; i < $result.length; i++) {
            cities[i] = $result[i][0];
            prodCopy[i] = Integer.valueOf($result[i][1]);
            products[i] = Integer.valueOf($result[i][1]);
        }

        Arrays.sort(products);

        for (int i = 0; i < products.length; i++) {
            int counter = -1;
            for (int p : prodCopy) {
                ++counter;
                if (p == products[i]) {
                    break; //breaks the loop to continue to other code without increasing counter
                }
            }
            $result[i][0] = cities[counter];
            $result[i][1] = "" + prodCopy[counter];
        }

        System.out.println("\nprinting full list sorted as counting of product");
        for (String[] k : $result) {
            System.out.println("City: " + k[0] + " have products " + k[1]);
        }

        int loc = $result.length - 2;
        System.out.println();
        System.out.println("Second highest City is '" + $result[loc][0] + "' having products '" + $result[loc][1] + "'");
        System.out.println();
    }

    public static void main(String... $results) {
        action1();
        action2();
    }
}

Answer 2

Use HashMap where key will be city and value will be the total count

1. Iterate over the array
2. If key exists, get the value of key and increment the count with new values
3. If key doesn't exist, push the value.

Here is the basic idea:

if(dataMap.get(city)==null){
  dataMap.put(city,value);
 }
else{
 dataMap.put(city,value+dataMap.get(city));
}

You can do the same thing with array as well, but you will need to declare a new array where you will be adding count based on the similar city name. The appropriate data structure for this scenario is HashMap