怎么用java二分查找數(shù)組具有相同的元素

要使用Java進行二分查找數(shù)組中具有相同元素的方法，首先需要確保數(shù)組已經按照升序或降序的方式排序。然后，可以使用以下代碼來實現(xiàn)二分查找：

public class BinarySearch {
    public static void main(String[] args) {
        int[] nums = {1, 2, 3, 3, 4, 5, 6};
        int target = 3;
        
        int left = binarySearchLeft(nums, target);
        int right = binarySearchRight(nums, target);
        
        if (left == -1 || right == -1) {
            System.out.println("No elements found.");
        } else {
            for (int i = left; i <= right; i++) {
                System.out.println("Element found at index: " + i);
            }
        }
    }
    
    public static int binarySearchLeft(int[] nums, int target) {
        int left = 0;
        int right = nums.length - 1;
        int index = -1;
        
        while (left <= right) {
            int mid = left + (right - left) / 2;
            
            if (nums[mid] == target) {
                index = mid;
                right = mid - 1;
            } else if (nums[mid] < target) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }
        
        return index;
    }
    
    public static int binarySearchRight(int[] nums, int target) {
        int left = 0;
        int right = nums.length - 1;
        int index = -1;
        
        while (left <= right) {
            int mid = left + (right - left) / 2;
            
            if (nums[mid] == target) {
                index = mid;
                left = mid + 1;
            } else if (nums[mid] < target) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }
        
        return index;
    }
}

在這個例子中，我們定義了兩個輔助函數(shù)binarySearchLeft和binarySearchRight來查找數(shù)組中具有相同元素的左右邊界。然后在main方法中調用這兩個函數(shù)，并打印出所有滿足條件的元素的索引。