p1578最后一个测试点WA了

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
using namespace std;
int a[100005],b[100005];
int n,m;
int main(){
    scanf("%d%d",&n,&m);
    for(int i=0;i<n;i++) scanf("%d",&a[i]);
    for(int i=0;i<m;i++) scanf("%d",&b[i]);
    sort(a,a+n);
    int tot=0;
    for(int i=0;i<m;i++){
        int zuo=0,you=n-1,ans=0x7fffffff,now=0;
        while(zuo<=you){
            int c=(zuo+you)/2;
            if(a[c]<b[i]){
                ans=min(ans,abs(b[i]-a[c]));
                zuo=c+1;
            }
            else{
                you=c-1;
                ans=min(ans,abs(b[i]-a[c]));
            }
        }
        tot+=ans;
    }
    printf("%d",tot);
}