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;
    
}