30分，剩下的全部Re,用的是二分啊，为什嘛还是超时

#include<iostream>
#include<algorithm>
using namespace std;
int m,n,score;
int a[1001];
long long sum=0;
int main()
{
    cin>>m>>n;
    for(int i=1;i<=m;i++)
    cin>>a[i];
    sort(a+1,a+1+m);
    for(int i=1;i<=n;i++)
    {
        cin>>score;
        int left=0,right=m+1;
        while(left<right)
        {
            int mid=left+(right-left)/2;
            if(a[mid]>score)
            right=mid;
            else
            left=mid+1;
        }
        if(score<=a[1])
        {
            sum+=a[1]-score;
        }
        else
        sum+=min(abs(a[left]-score),abs(a[left-1]-score));
    }
    cout<<sum;

}