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 mid = L + ((R - L) >> 1); if (sortedArr[mid] == num) { return true; } else if (sortedArr[mid] > num) { R = mid - 1; } else { L = mid + 1; } } 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!"); } }