如何从两个数组中删除重复项？

Question

我需要一种算法来更改一个数组中的值（如果它在第二个数组中）。结果是第一个数组不应包含第二个数组中的任何值。

数组的长度是随机的（平均每个数组从0到15个整数），每个数组的内容是一个排序数字的列表，范围从0到90。

public void clearDuplicates(int[] A, int[] B){
    for(int i = 0; i < A.length; i++){
        for(int j = 0; j < B.length; j++)
            if(A[i] == B[j])
                A[i]++;
    }
}

我当前的代码没有清除所有重复项。最重要的是，它可能会创建一个超出范围的索引，或者内容可以超过 90。

Answer 1

也许你应该试试下面的代码：

public void clear (int[] A, int[] B)
{
  for (int i=0; i<A.length;i++)
  {
     for (int j=0; j<B.length; j++)
         if(A[i]==B[j])
         {
           for (int k=i; k<A.length;k++)
           A[k]=A[k+1];
           j=B.length-1; //so that the cycle for will not be executed
    }
  }
}

Answer 2

虽然你的问题不是很清楚，但这个应该可以解决问题。假设：

A和B中的整数个数小于90
数组A之后没有排序（如果你想使用Arrays.sort() 解决这个问题）。

之后数组 A 本身可能包含重复项。

public void clearDuplicates(int[] A, int[] B) {
    // Initialize a set of numbers which are not in B to all numbers 0--90
    final Set<Integer> notInB = new HashSet<>();
    for (int i = 0; i <= 90; i++) {
        notInB.add(i);
    }
    // Create a set of numbers which are in B. Since lookups in hash set are
    // O(1), this will be much more efficient than manually searching over B
    // each time. At the same time, remove elements which are in B from the
    // set of elements not in B.
    final Set<Integer> bSet = new HashSet<>();
    for (final int b : B) {
        bSet.add(b);
        notInB.remove(b);
    }

    // Search and remove duplicates
    for (int i = 0; i < A.length; i++) {
        if (bSet.contains(A[i])) {
            // Try to replace the duplicate by a number not in B
            if (!notInB.isEmpty()) {
                A[i] = notInB.iterator().next();
                // Remove the added value from notInB
                notInB.remove(A[i]);
            }
            // If not possible, return - there is no way to remove the
            // duplicates with the given constraints
            else {
                return;
            }
        }
    }
}

Answer 3

你可以通过使用 int[ ] 来完成，虽然它有点麻烦。唯一的限制是 B 本身不能有重复项。

public void clearDuplicates(int[] A, int[] B) {
    //Number of duplicates
    int duplicate = 0;
    //First you need to find the number of duplicates
    for (int i = 0; i < A.length; i++) {
        for (int j = 0; j < B.length; j++)
            if (A[i] == B[j]) 
                duplicate++;
    }
    //New A without duplicates
    int[] newA = new int[A.length-duplicate];
    //For indexing elements in the new A
    int notDuplicate = 0;
    //For knowing if it is or isn't a duplicate
    boolean check;
    //Filling the new A (without duplicates)
    for (int i = 0; i < A.length; i++) {
        check = true;
        for (int j = 0; j < B.length; j++) {
            if (A[i] == B[j]) {
                check = false;
                notDuplicate--;//Adjusting the index
            }
        }
        //Put this element in the new array
        if(check)
            newA[notDuplicate] = A[i];

        notDuplicate++;//Adjusting the index
    }
}

Answer 4

public class 复制删除 {

public static void main(String[] args) {
    int[] A = { 1, 8, 3, 4, 5, 6 };
    int[] B = { 1, 4 };
    print(clear(A, B));
}

public static int[] clear(int[] A, int[] B) {
    int a = 0;
    for (int i = 0; i < A.length; i++) {
        for (int j = 0; j < B.length; j++) {
            if (A[i] == B[j]) {
                a++;
                for (int k = i; k < A.length - a; k++) {
                    A[k] = A[k + 1];
                }
            }
        }

    }
    int[] C = new int[A.length - a];
    for (int p = 0; p < C.length; p++)
        C[p] = A[p];
    return C;

}

public static void print(int[] A) {
    for (int i = 0; i < A.length; i++)
        System.out.println("Element: " + A[i]);
}

} 这是一个例子..我编译了它的工作。如有任何问题，请告诉我 :)

如何从两个数组中删除重复项？

How do I remove duplicates from two arrays?

java

arrays