怎么用java二分查找数组具有相同的元素-开发者知识库平台

怎么用java二分查找数组具有相同的元素

Java

709

2024/2/16 17:05:31

栏目: 编程语言

要使用Java进行二分查找数组中具有相同元素的方法，首先需要确保数组已经按照升序或降序的方式排序。然后，可以使用以下代码来实现二分查找：

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;
    }
}

在这个例子中，我们定义了两个辅助函数binarySearchLeft和binarySearchRight来查找数组中具有相同元素的左右边界。然后在main方法中调用这两个函数，并打印出所有满足条件的元素的索引。

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怎么用java二分查找数组具有相同的元素

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