P1678，求DALAO(初中生的疑惑)

求DALAO看一看

#include<iostream>
#include<cstring>
#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
int school,student,start=0;
int range_score[1000010],answer=0;
int school_score[1000010];
int main(){
    cin>>school>>student;
    for(int i=0;i<school;i++){cin>>school_score[i];}
    for(int i=0;i<student;i++){cin>>range_score[i];}
    sort(range_score,range_score+student);
    sort(school_score,school_score+school);
    for(int i=0;i<student;i++){
        for(int j=start;j<school;j++){
            if(school_score[j]>range_score[i]){
                if(range_score[i]-school_score[j-1]>=school_score[j]-range_score[i]){
                    answer+=school_score[j]-range_score[i];
                    start=school_score[j];
                }else{
                    answer+=range_score[i]-school_score[j-1];
                    start=school_score[j-1];
                }
                break;
            }
        }
    }
    cout<<answer;
    return 0;
}

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