08在arr上，返回小于等于targetNum的最右的位置.zip

package class01; import java.util.Arrays; /** * 在arr上，返回小于等于targetNum的最右的位置。 * 如果没有则返回-1。 */ public class Code06_BSNearRight { public static int nearestIndex(int[] arr, int targetNum) { int L = 0; int R = arr.length - 1; int temp = -1; while (L <= R) { int mid = L + ((R - L) >> 1); if (arr[mid] <= targetNum) { temp = mid; L = mid + 1; } else { R = mid - 1; } } return temp; } public static int[] generateRandomArr(int maxSize, int maxValue) { int[] arr = new int[(int) (Math.random() * maxSize)]; for (int i = 0; i < arr.length; i++) { arr[i] = (int) (Math.random() * maxValue) - (int) (Math.random() * maxValue); } return arr; } public static void printArr(int[] arr) { for (int i = 0; i < arr.length; i++) { System.out.print(arr[i] + "\t"); } System.out.println(); } public static int test(int[] arr, int targetNum) { for (int i = arr.length - 1; i >= 0; i--) { if (arr[i] <= targetNum) { return i; } } return -1; } public static int[] copyArr(int[] arr1) { int[] arr2 = new int[arr1.length]; for (int i = 0; i < arr1.length; i++) { arr2[i] = arr1[i]; } return arr2; } public static void main(String[] args) { int testTimes = 1000000; int maxSize = 100; int maxValue = 100; boolean flag = true; for (int i = 0; i < testTimes; i++) { int[] arr1 = generateRandomArr(maxSize, maxValue); int[] arr2 = copyArr(arr1); Arrays.sort(arr2); int targetNum = (int) (Math.random() * maxValue); int resultNum = nearestIndex(arr2, targetNum); int testNum = test(arr2, targetNum); if (resultNum != testNum) { System.out.println("oops!"); flag = isFlag(arr1, arr2, targetNum, resultNum, testNum); } } int targetNum = (int) (Math.random() * maxValue); int[] arr1 = generateRandomArr(maxSize, maxValue); int[] arr2 = copyArr(arr1); Arrays.sort(arr2); int resultNum = nearestIndex(arr2, targetNum); int testNum = test(arr2, targetNum); boolean flag1 = isFlag(arr1, arr2, targetNum, resultNum, testNum); System.out.println(flag ? "nice!" : "oops!"); } private static boolean isFlag(int[] arr1, int[] arr2, int targetNum, int resultNum, int testNum) { System.out.println("============================================================"); System.out.print("原来的数组："); printArr(arr1); System.out.print("升序后数组："); printArr(arr2); System.out.print("数组的索引："); for (int i = 0; i < arr1.length; i++) {//索引 System.out.print(i + "\t"); } System.out.println(); System.out.println("targetNum = " + targetNum); System.out.println("resultNum = " + resultNum); System.out.println("testNum = " + testNum); System.out.println("============================================================"); return false; } }