#include <bits/stdc++.h>
using namespace std;
const int N = 10;
int arr[N] = {1, 2, 4, 4, 4, 6, 8, 10};
const int n = 8;
const int target = 4;

int main() {
    // lower_bound
    int *lower = lower_bound(arr, arr + n, target);
    cout << "lower_bound of " << target << " is at index: " << (lower - arr) << endl;

    // upper_bound
    int *upper = upper_bound(arr, arr + n, target);
    cout << "upper_bound of " << target << " is at index: " << (upper - arr) << endl;

    // 找到最后一个小于 target 的元素
    if (lower != arr) {
        int *last_less = lower - 1;
        cout << "Last element less than " << target << " is " << *last_less << " at index " << (last_less - arr) << endl;
    } else {
        cout << "No element is less than " << target << endl;
    }

    // 找到最后一个小于等于 target 的元素
    if (upper != arr) {
        int *last_less_equal = upper - 1;
        cout << "Last element less than or equal to " << target << " is " << *last_less_equal
             << " at index " << (last_less_equal - arr) << endl;
    } else {
        cout << "No element is less than or equal to " << target << endl;
    }

    // 查找元素是否存在
    if (lower != arr + n && *lower == target)
        cout << target << " exists in the array at index " << (lower - arr) << endl;
    else
        cout << target << " does not exist in the array." << endl;

    // 统计目标值出现个数
    int count = upper - lower;
    cout << "Count of " << target << " is: " << count << endl;

    return 0;
}