80pts啊啊啊

#include <bits/stdc++.h>
using namespace std;

const int maxn = 2e5 + 10;
typedef long long ll;

struct Node {
	ll l;
	int id;
	bool operator <(const Node &T) const {
		return l < T.l;
	}
};

Node t[maxn];
ll a[maxn], b[maxn], r[maxn];
ll n, m, rmax, ans = 1e16;

inline ll read() {
	ll x = 0, f = 1;
	char ch = getchar();
	while (!isdigit(ch)) {
		if (ch == '-') f = -1;
		ch = getchar();
	}
	while (isdigit(ch)) {
		x = (x * 10) + (ch ^ 48);
		ch = getchar();
	}
	return x * f;
}

int main() {
	n = read(), m = read();
	for (int i = 1; i <= n; i++) a[i] = read();
	b[0] = -1e16;
	b[m + 1] = 1e16;
	
	for (int i = 1; i <= m; i++) b[i] = read();
	sort(b + 1, b + m + 1);
	
	for (int i = 1; i <= n; i++) {
		t[i].l = a[i] - b[upper_bound(b + 1, b + m + 1, a[i]) - b - 1];
		t[i].id = i;
		r[i] = b[upper_bound(b + 1, b + m + 1, a[i]) - b] - a[i];
	}
	
	sort(t + 1, t + n + 1);
	for (int i = n; i >= 1; i--) {
		ans = min(ans, min(t[i].l * 2 + rmax, rmax * 2 + t[i].l));
		rmax = max(r[t[i].id], rmax);
	}
	
	printf("%lld\n", ans);
	return 0;
}

这是本蒟蒻的代码，求调，必关！！！