二分查找，只有60分，#2，#3，#9，#10没过，请求高手支援

#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
using namespace std;
int m, n;
vector<int> school;
vector<int> student;
vector<int> my_index;
int check(int school_index, int student_index);
int binary_search(int x);
int main() {
    cin >> m >> n;
    for (int i = 1; i <= m; i++) {
        int x;
        cin >> x;
        school.push_back(x);
    }
    for (int i = 1; i <= n; i++) {
        int x;
        cin >> x;
        student.push_back(x);
    }
    sort(school.begin(), school.end());
    sort(student.begin(), student.end());
    for (int i = 0; i <= n - 1; i++) {
        my_index.push_back(binary_search(i));
    }
    long long int ans = 0;
    for (int i = 0; i <= n - 1; i++) {
        if (i - 1 < 0) {
            ans += school[my_index[i]] - student[i];
        } else {
            ans += min(school[my_index[i]] - student[i],
                       student[i] - school[my_index[i]-1]);
        }
    }
    cout << ans;
    return 0;
}
int binary_search(int x) {
    int ans = 0;
    int left = 0;
    int right = m - 1;
    while (left <= right) {
        int mid = (left + right) >> 1;
        if (check(mid, x)) {
            ans = mid;
            right = mid - 1;
        } else {
            left = mid + 1;
        }
    }
    return ans;
}
int check(int school_index, int student_index) {
    if (student[student_index] <= school[school_index]) {
        return 1;
    } else {
        return 0;
    }
}