package Test; public class Test { //用最小的内存查找数组中是否存在这个数 public static void main(String[] args) { int [] arr = {12,2,3,4,5,6,7,8,90,76,43}; byte[] byt = new byte[100]; for (int i = 0; i < arr.length; i++) { byt[arr[i]] = 1; } int n = 13; if(byt[n] == 1) { System.out.println("存在"); }else { System.out.println("不存在"); } System.out.println("=========================="); Test t = new Test(); t.paixu(arr, 29); } //用二分法查找这个数组中是否存在这个数 public int paixu(int[] arr,int x) { System.out.println(arr); int min = 0; int max = arr.length -1; while(min<=max) { int middle = (min + max)/2; if(x == arr[middle]) { return middle;//返回该下标 }else if(x < arr[middle]) { max = middle-1; }else { max = middle+1; } } return -1; } }