4、折半查找

折半查找,提高效率,但是必须要保证该数组是有序排列

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示例：

class Other {public static void main(String[] args) {int[] arr = new int[]{5,3,6,8,4,6,9,2};int pos = halfSearch(arr,9);System.out.println(pos);}public static int halfSearch(int[] arr,int key){int min = 0;int max = arr.length-1;int mid;while(min <= max){mid =(min + max)/2;if(arr[mid] > key) max = mid;else if(arr[mid] < key)min = mid;elsereturn mid;}return -1;}}

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