二分查找（java)

import java.util.Scanner;

public class Main {
    static int[] arr;

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        int q = scan.nextInt();
        arr = new int[n + 1];
        for (int i = 1; i <= n; i++) {
            arr[i] = scan.nextInt();
        }
        while (q-- > 0) {
            int id = scan.nextInt();
            int l = scan.nextInt();
            int r = scan.nextInt();
            int x = scan.nextInt();
            if (id == 1) {
                System.out.println(index1(l, r, x));
            }
            if (id == 2) {
                System.out.println(index2(l, r, x));
            }
            if (id == 3) {
                System.out.println(index3(l, r, x));
            }
            if (id == 4) {
                System.out.println(index4(l, r, x));
            }
        }
    }

    public static int index1(int l, int r, int x) {
        int left = l;
        int right = r;
        int index = -1;
        while (left <= right) {
            int mid = (left + right) / 2;
            if (arr[mid] == x) {
                index = mid;
                right = mid - 1;
            } else if (arr[mid] > x) {
                right = mid - 1;
            } else {
                left = mid + 1;
            }
        }
        return index;
    }

    public static int index2(int l, int r, int x) {
        int left = l;
        int right = r;
        int index = -1;
        while (left <= right) {
            int mid = (left + right) / 2;
            if (arr[mid] == x) {
                index = mid;
                left = mid + 1;
            } else if (arr[mid] < x) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }
        return index;
    }

    public static int index3(int l, int r, int x) {
        int left = l;
        int right = r;
        int index = -1;
        while (left <= right) {
            int mid = (left + right) / 2;
            if (arr[mid] >= x) {
                index = mid;
                right = mid - 1;
            } else {
                left = mid + 1;
            }
        }
        return index;
    }

    public static int index4(int l, int r, int x) {
        int left = l;
        int right = r;
        int index = -1;
        while (left <= right) {
            int mid = (left + right) / 2;
            if (arr[mid] > x) {
                index = mid;
                right = mid - 1;
            } else {
                left = mid + 1;
            }
        }
        return index;
    }
}