合并两个数组并删除Java中的重复项 [英] Merge two arrays and remove duplicates in Java

问题描述

我无法从已合并为一个的两个阵列中删除重复项。我编写了以下代码来合并数组，但我不知道如何从最终数组中删除重复项。假设数组已经排序。

I am having trouble removing the duplicates from two arrays that have been merged into one. I have written the following code that merges the arrays, yet I'm not sure how to remove the duplicates from the final array. Assume the arrays are already sorted.

public static int[] merge(int[] list1, int[] list2) {
    int[] result = new int[list1.length + list2.length];

    int i = 0;
    int j = 0;

    for (int k = 0; k < (list1.length + list2.length); k++) {
        if (i >= list1.length) {
            result[k] = list2[j];
            j++;
        } 
        else if (j >= list2.length) {
            result[k] = list1[i];
            i++;
        } 
        else {
            if (list1[i] < list2[j]) {
                result[k] = list1[i];
                i++;
            } else {
                result[k] = list2[j];
                j++;
            }
        }
    }
    return result;
}

推荐答案

好的，有人讨厌所有的答案。这是另一个结合两个stackoverflow q的尝试，组合数组和去除欺骗。

Ok, someone hated all the answers. Here's another attempt that combines two stackoverflow q's, combining arrays and removing dupes.

这个比我之前尝试的两百万个整数列表运行得更快。

This one runs a good deal faster than my earlier attempt on two lists of a million ints.

public int[] mergeArrays2(int[] arr1, int[] arr2){
    int[] merged = new int[arr1.length + arr2.length];
    System.arraycopy(arr1, 0, merged, 0, arr1.length);
    System.arraycopy(arr2, 0, merged, arr1.length, arr2.length);

    Set<Integer> nodupes = new HashSet<Integer>();

    for(int i=0;i<merged.length;i++){
        nodupes.add(merged[i]);
    }

    int[] nodupesarray = new int[nodupes.size()];
    int i = 0;
    Iterator<Integer> it = nodupes.iterator();
    while(it.hasNext()){
        nodupesarray[i] = it.next();
        i++;
    }



    return nodupesarray;
}

控制台输出：

INFO [main] (TestMergeArray.java:40) - creating two lists of a million ints
DEBUG [main] (TestMergeArray.java:41) - list 1 size : 1000000
DEBUG [main] (TestMergeArray.java:42) - list 2 size : 1000000
INFO [main] (TestMergeArray.java:56) - now merging
INFO [main] (TestMergeArray.java:59) - done, final list size is 864975

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