蒟蒻求助，70分

咋就错了？ 源码：

#include <bits/stdc++.h>

using namespace std;

int a[100001], b[100001];
int m, n, ans = 0;

int sovel(int a[])
{
    int mid,j;
    for (j = 1;j <= n;++j)
    {
        int left = 0, right = m + 1;
        while (left < right)
        {
            mid = (left + right) / 2;
            if (a[mid] <= b[j]) left = mid + 1;
            else right = mid;
        }
        ans += abs(a[left - 1] - b[j]) < abs(a[left] - b[j]) ? abs(a[left - 1] - b[j]) : abs(a[left] - b[j]);
    }
    return ans;
}

int main()
{
    int i;
    cin >> m >> n;
    for (i = 1;i <= m;++i)
        cin >> a[i];
    for (i = 1;i <= n;++i)
        cin >> b[i];
    sort(a + 1, a + m + 1);
    cout << sovel(a);
    return 0;
}

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