package class03; import java.util.Arrays; public class Code02_BSNearLeft { // arr有序的,>=num 最左 public static int mostLeftNoLessNumIndex(int[] arr, int num) { if (arr == null || arr.length == 0) { return -1; } int L = 0; int R = arr.length - 1; int ans = -1; while (L <= R) { int mid = (L + R) / 2; if (arr[mid] >= num) { ans = mid; R = mid - 1; } else { L = mid + 1; } } return ans; } // for test public static int test(int[] arr, int value) { for (int i = 0; i < arr.length; i++) { if (arr[i] >= value) { return i; } } return -1; } // 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; } // for test public static void printArray(int[] arr) { if (arr == null) { return; } for (int i = 0; i < arr.length; i++) { System.out.print(arr[i] + " "); } System.out.println(); } 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) != mostLeftNoLessNumIndex(arr, value)) { printArray(arr); System.out.println(value); System.out.println(test(arr, value)); System.out.println(mostLeftNoLessNumIndex(arr, value)); succeed = false; break; } } System.out.println(succeed ? "Nice!" : "Fucking fucked!"); } }