70分，哪儿有问题；佬们

#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>

using namespace std;

const int N = 1e5 + 10;

int arr[N], rell[N];

int n, m;

int main()
{
    //m为学校数，n为学生数
    cin >> m >> n;

    //arr[i]表示学校预计录取分数线
    //rell[i]表示学生估分
    for (int i = 0; i < m; i++) cin >> arr[i];

    sort(arr, arr + m);

    long long res = 0;
    for (int  i= 0; i < n; i++)
    {
        cin >> rell[i];
        int l = 0, r = m - 1;
        while (l < r)
        {
            int mid = l + r >> 1;
            if (arr[mid] >= rell[i])    r = mid;
            else    l = mid + 1;
        }
        res += min(abs(arr[l] - rell[i]), min(abs(arr[l - 1] - rell[i]), abs(arr[l+1] - rell[i])));
    }

    cout << res << endl;

    return 0;
}