對陣列的二分搜索在java上給出錯誤的索引

我正在撰寫一個不必匯入 java Arrays的代碼，它可以插入、洗掉和搜索一系列值；但是輸出會列印出在binSearch()呼叫該方法時找不到串列中的值。在呼叫之前，我已經在 main 方法中對陣列進行了排序，binSearch()但它仍然沒有找到值的索引。

我仍然是java.

private static int[] insertElement(int index, int array[], int list[], int i) {
    int length = array.length;
    int destination[] = new int[length   1];
    for (int j = 0; j < destination.length; j  ) {
        System.arraycopy(array, 0, destination, 0, index);
        System.arraycopy(array, index, destination, index   1, length - index);
    }
    destination[index] = list[i];
    System.out.println(list[i]   " is inserted in the list.");
    return destination;
}

private static int[] deleteElement(int index, int[] array, int list[], int i) {
    boolean[] deleteNumber = new boolean[array.length];
    int size = 0;
    for (int j = 0; j < array.length; j  ) {
        if (array[j] == list[i]) {
            deleteNumber[j] = true;
            System.out.println(list[i]   " is removed from the list.");
        }
        else {
            deleteNumber[j] = false;
            size  ;
        }
    }
    
    int[] newArr = new int[size];
    int in = 0;
    for (int j = 0; j < array.length; j  ) {
        if (!deleteNumber[j]) {
            newArr[in  ] = array[j];
        }
    }
    return newArr;
}

public static int binSearch(int[] array, int search[], int i) {
    int left = 0;
    int right = array.length - 1;
    
    if (left <= right) {
        int middle = (left   right) / 2;
        if (search[i] < array[middle]) {
            right = middle - 1;
        }
        else if (search[i] > array[middle]) {
            left = middle   1;
        }
        else {
            System.out.print(search[i]   " is found at location ");
            return middle;
        }
    }
    return -1;
}

 public static void main(String args[]) {
    int arr[] = {2, 4, 6, 8, 9, 10, 20, 33, 44, 45, 68, 88};
    int index = 1;
    
    //insert element
    int newIndex = index - 1;
    int s[] = {3, 78, 98, 12};
    for (int i = 0; i < s.length; i  ) {
        arr = insertElement(newIndex, arr, s, i);
    }
    
    //delete element
    int d[] = {20, 44, 89};
    for (int i = 0; i < d.length; i  ) {
        arr = deleteElement(newIndex, arr, d, i);
    }
    
    //sort the array
    for (int i = 0; i < arr.length; i  ) {
        for (int j = i   1; j < arr.length; j  ) {
            if (arr[i] > arr[j]) {
                int swap = arr[i];
                arr[i] = arr[j];
                arr[j] = swap;
            }
        }
    }
    
    //search for element in array
    BinarySearch ob = new BinarySearch();
    int a[] = {8, 45, 88, 90};
    for (int i = 0; i < a.length; i  ) {
        int result = ob.binSearch(arr, a, i);
        if (result == -1) {
            System.out.println(a[i]   " is not found in the list.");
        }
        else {
            System.out.println(result   ".");
        }
    }
    //print array
    printArray(arr);
}

uj5u.com熱心網友回復：

只需用 while 替換 if 子句，因為您必須在二叉搜索樹的所有級別進行搜索。改變

if (left <= right)

到

while (left <= right)

而且您的 insertElement 方法中也存在小問題。

for (int j = 0; j < destination.length; j  ) {
            System.arraycopy(array, 0, destination, 0, index);
            System.arraycopy(array, index, destination, index   1, length - index);
        }

在 insertElement 方法中不再需要 for 回圈，因為您已經在回圈遍歷需要添加到 main 方法中的陣列。

uj5u.com熱心網友回復：

我在我的代碼中發現了錯誤。binSearch() 方法應該使用while回圈，而不是 if 回圈。整個代碼現在完美運行。

    public static int binSearch(int[] array, int search[], int i) {
        int left = 0;
        int right = array.length - 1;
        
        while (left <= right) {
            int middle = (left   right) / 2;
            if (search[i] < array[middle]) {
                right = middle - 1;
            }
            else if (search[i] > array[middle]) {
                left = middle   1;
            }
            else {
                System.out.print(search[i]   " is found at location ");
                return middle;
            }
        }
        return -1;
    }

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