How many identical numbers in two arrays

Question

Two arrays are given. It is necessary to calculate how many numbers are contained simultaneously in both the first and second arrays and output them in ascending order.

Note: If there is a number in the first array (for example, 1), and in the second array this number occurs twice (for example, an array of 5 elements: 1,2,3,4,1 ), then in this case the number 1 is 1 times in both arrays. If the number occurs several times in each array, then it is still one match.

My code is:

 package shestnadcat; import java.util.Scanner; public class Shestnadcat2 { public static void main(String[] args) { Scanner in = new Scanner(System.in); System.out.println("Введите количество элементов первого массива"); int b = in.nextInt(); int i; int[] a = new int[b]; for (i = 0; i < b; i++) { System.out.println("Введите элемент " + i); a[i] = in.nextInt(); } System.out.println("Введите количество элементов второго массива"); int d = in.nextInt(); int[] c = new int[d]; for (i = 0; i < d; i++) { System.out.println("Введите элемент " + i); c[i] = in.nextInt(); } int k = 0; for (i = 0; i < b; i++) { int g = a[i]; for (i = 0; i < d; i++) { if (g == c[i]) { k = +1; } } } System.out.println(k); } }

The counter incorrectly displays the result.

I can not think of the output of these numbers.

Счётчик неправильно выводит результат.
You have counter i in two cycles, but it should be different .... standard i and j
In arrays {1, 1, 1} and {1, 1, 1} how many identical numbers?

Regent regent 17.7k five 22 39 · Accepted Answer · 2016-12-27T09:44:39

 public static void main(String[] args) { Scanner in = new Scanner(System.in); int[] firstArray = readArray(in, "первого"); int[] secondArray = readArray(in, "второго"); //создание массива отметок о найденных совпадениях во втором массиве boolean[] secondMatches = new boolean[secondArray.length]; for (int i = 0; i < secondMatches.length; i++) { secondMatches[i] = false; } int matchesCount = 0; //поиск совпадений for (int firstElement : firstArray) { for (int i = 0; i < secondArray.length; i++) { if (firstElement == secondArray[i]) { if (!secondMatches[i]) { secondMatches[i] = true; matchesCount++; } break; } } } //создание массива совпадений int[] matches = new int[matchesCount]; int k = 0; for (int i = 0; i < secondArray.length; i++) { if (secondMatches[i]) { matches[k++] = secondArray[i]; } } //сортировка пузырьком массива совпадений for (int i = matches.length - 1; i >= 0; i--) { for (int j = 0; j < i; j++) { if (matches[j] > matches[j + 1]) { int swap = matches[j]; matches[j] = matches[j + 1]; matches[j + 1] = swap; } } } System.out.println(matchesCount); for (int element : matches) { System.out.print(element + " "); } } private static int[] readArray(Scanner in, String arrayNumberName) { System.out.println("Введите количество элементов " + arrayNumberName + " массива"); int elementsCount = in.nextInt(); int[] elements = new int[elementsCount]; for (int i = 0; i < elementsCount; i++) { System.out.println("Введите элемент " + i); elements[i] = in.nextInt(); } return elements; }

And, by the way, try to use meaningful variable names in the future and not save on spaces.

Answer 2 · 2016-12-27T09:38:06

It is necessary to shove all the values in the HashMap and compare the size of the HashMap with the number of entries in both arrays:

 int[] firstArray = new int[]{1, 3, 4, 5, 56, 6}; int[] secondArray = new int[]{11, 8, 3, 4, 5, 56, 6}; HashMap hashmap=new HashMap<String, Integer>(); for(int i=0; i < firstArray.length; i++) hashmap.put(new Integer(firstArray[i]).toString(), new Integer(firstArray[i])); for(int i=0; i < secondArray.length; i++) hashmap.put(new Integer(secondArray[i]).toString(), new Integer(secondArray[i])); System.out.println("Совпадающих значений="+(firstArray.length+secondArray.length)-hashmap.size()));

user207618 · Answer 3 · 2016-12-26T20:22:25

 import java.util.*; public class Main { public static void main(String[] args) { ArrayList<Integer> first = new ArrayList<Integer>(); ArrayList<Integer> second = new ArrayList<Integer>(); first.add(1); first.add(2); first.add(3); first.add(42); second.add(3); second.add(4); second.add(5); second.add(42); second.retainAll(first); Collections.sort(second); System.out.println(second); } }

Visually see .

@ Alexey Shimansky, which may be altered under the lists in order to work as a white person.
I did not understand anything from the code ... I am in primitives (can you simplify?
@MaratZimnurov with primitives is just the opposite - there will be a lot of code.
@ Alexey Shimansky is not important (the main thing is to be)

Answer 4 · 2016-12-27T09:22:25

Option with stream api:

 int[] firstArray = new int[]{1, 3, 4, 5, 56, 6}; int[] secondArray = new int[]{11, 8, 3, 4, 5, 56, 6}; IntStream .concat(Arrays.stream(firstArray), Arrays.stream(secondArray)) .distinct() .sorted() .forEach(System.out::println);

A little confused and wrote a small implementation of streams:

 private static class CustomIntStream { private final int[] array; public CustomIntStream(int[] array) { this.array = array; } @Override public String toString() { return Arrays.toString(array); } public static CustomIntStream of(int[] firstArray, int[] secondArray) { int[] array = new int[firstArray.length + secondArray.length]; System.arraycopy(firstArray, 0, array, 0, firstArray.length); System.arraycopy(secondArray, 0, array, firstArray.length, secondArray.length); return new CustomIntStream(array); } public CustomIntStream distinct() { int[] buffer = new int[array.length]; int index = 0; for (int i = 0; i < array.length; i++) { boolean isContains = false; for (int j = i + 1; j < array.length; j++) if (isContains = (array[i] == array[j])) break; if (!isContains) buffer[index++] = array[i]; } int[] newArray = new int[index]; System.arraycopy(buffer, 0, newArray, 0, newArray.length); return new CustomIntStream(newArray); } public CustomIntStream sorted() { int[] newArray = new int[array.length]; System.arraycopy(array, 0, newArray, 0, array.length); sort(newArray, 0, newArray.length - 1); return new CustomIntStream(newArray); } private static void sort(int[] array, int start, int end) { int middle = (end - start) / 2 + start; int left = start; int right = end; while (left < right) { while (left <= end && array[middle] > array[left]) left++; while (right >= start && array[middle] < array[right]) right--; if (left <= right) { int buffer = array[left]; array[left] = array[right]; array[right] = buffer; right--; left++; } } if (start < right) sort(array, start, right); if (left < end) sort(array, left, end); } public void foreach(IntConsumer consumer) { for (int i = 0; i < array.length; i++) consumer.accept(array[i]); } }

Used similarly:

 CustomIntStream .of(firstArray, secondArray) .distinct() .sorted() .foreach(System.out::println);

How many identical numbers in two arrays

4 answers 4

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