二分查找

二分查找

必须值得注意的是: 数组必须有序

//数组必须有序public static int get3(int[] arr, int find){//定义两个索引 分别指向数组的两端int start = 0;int end = arr.length-1;//这里必须有 等于while (start <= end){int mid = (start + end) / 2;if (arr[mid] == find) return mid+1;else if (arr[mid] > find)end = mid-1;elsestart =  mid + 1;}return -1;}