https://ac.nowcoder.com/acm/contest/322/J

题解：二分给我搜。。。。

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,q;
ll ans;
ll a[N];
ll b[N];
char str;
bool sloved(ll mid){
    int x=1;
    for(int i=1;i<=n;i++){//cout<<x;
        while(abs(a[i]-b[x])>mid){
            x++;
            if(x>m)
                break;
        }
        if(x>m)
            break;
    }
    if(x<=m)
        return 1;
    return 0;

}
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++){
        scanf("%lld",&a[i]);
    }
    for(int i=1;i<=m;i++){
        scanf("%lld",&b[i]);
    }
    sort(a+1,a+n+1);
    sort(b+1,b+m+1);
    ll l=0;
    ll r=4e9+N;
    ll mid;
    while(l<=r){
        mid=(l+r)>>1;
        if(sloved(mid)){
                ans=mid;
            r=mid-1;
        }else{
            l=mid+1;
        }
    }
    cout << ans << endl;
    //cout << "Hello world!" << endl;
    return 0;
}