package class01;
import java.util.Arrays;
public class Code04_BSExist {
public static boolean exist(int[] sortedArr, int num) {
if (sortedArr == null || sortedArr.length == 0) {
return false;
}
int L = 0;
int R = sortedArr.length - 1;
int mid = 0;
// L..R
while (L < R) { // L..R 至少两个数的时候
//算出中点
mid = L + ((R - L) >> 1);
//判断是否找到
if (sortedArr[mid] == num) {
return true;
} else if (sortedArr[mid] > num) {
R = mid - 1;
} else {
L = mid + 1;
}
}
//因为除法都是向下取的 比如 3-0 除 2 = 1 因为 011 >> 1 = 001 所以min 是1
//如果是1位置数 大与 那就剩下0了
return sortedArr[L] == num;
}
// for test
public static boolean test(int[] sortedArr, int num) {
for(int cur : sortedArr) {
if(cur == num) {
return true;
}
}
return false;
}
// for test
public static int[] generateRandomArray(int maxSize, int maxValue) {
int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
for (int i = 0; i < arr.length; i++) {
arr[i] = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
}
return arr;
}
public static void main(String[] args) {
int testTime = 500000;
int maxSize = 10;
int maxValue = 100;
boolean succeed = true;
for (int i = 0; i < testTime; i++) {
int[] arr = generateRandomArray(maxSize, maxValue);
Arrays.sort(arr);
int value = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
if (test(arr, value) != exist(arr, value)) {
succeed = false;
break;
}
}
System.out.println(succeed ? "Nice!" : "Fucking fucked!");
}
}
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