P1678 烦恼的高考志愿 二分

import java.util.Arrays;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();
		int[] a = new int[n+1];//学校
		int[] b = new int[m+1];//学生
		for(int i=1;i<=n;i++) {
			a[i] = sc.nextInt();
		}
		for(int i=1;i<=m;i++) {
			b[i] = sc.nextInt();
		}
		Arrays.sort(a,1,n+1);
		Arrays.sort(b,1,m+1);
		
		long sum = 0;
		for(int i=1;i<=m;i++) {//枚举学生
			int l = 1, r = n;
			while(l<r) {
				int mid = (l+r)/2;
				if(a[mid]>=b[i]) r = mid;
				else l = mid+1;
			}//找到第一个大于等于学生分数的学校
			if(l == 1)
				sum+=a[1]-b[i];
			if(l>=2)
				sum+=Math.min(Math.abs(a[l]-b[i]),Math.abs(a[l-1]-b[i]));
		}
		System.out.println(sum);
	}
}