二分查找

//二分查找 public static void main(String[] args) { int [] arr = {1,2,5,9,11,16}; Scanner sc = new Scanner(System.in); System.out.println("请输入要查找的数字"); int x = sc.nextInt(); int left = 0; int right = arr.length-1; int mid = (left + right) /2; boolean flag = true; while(left<=right){ if(x == arr[mid]){ System.out.println("找到了，下标是" + mid); flag = false; break; }else if(x <arr[mid]){ right=mid-1; }else{ left =mid+1; } mid = (left + right)/2; } System.out.println(flag?"找不到":""); }