在arr上，返回小于等于targetNum的最右的位置。

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;
    }
}