【CodeForces 830A】Office Keys

A. Office Keys

time limit per test
2 seconds

memory limit per test
256 megabytes

input
standard input

output
standard output

There are n people and k keys
on a straight line. Every person wants to get to the office which is located on the line as well. To do that, he needs to reach some point with a key, take the key and then go to the office. Once a key is taken by somebody, it couldn't be taken by anybody
else.
You are to determine the minimum time needed for all n people
to get to the office with keys. Assume that people move a unit distance per 1 second. If two people reach a key at
the same time, only one of them can take the key. A person can pass through a point with a key without taking it.

Input
The first line contains three integers n, k and p (1 ≤ n ≤ 1 000, n ≤ k ≤ 2 000, 1 ≤ p ≤ 109)
— the number of people, the number of keys and the office location.
The second line contains n distinct
integers a1, a2, ..., an (1 ≤ ai ≤ 109)
— positions in which people are located initially. The positions are given in arbitrary order.
The third line contains k distinct
integers b1, b2, ..., bk (1 ≤ bj ≤ 109)
— positions of the keys. The positions are given in arbitrary order.
Note that there can't be more than one person or more than one key in the same point. A person and a key can be located in the same point.

Output
Print the minimum time (in seconds) needed for all n to
reach the office with keys.

Examples

input

2 4 50
20 100
60 10 40 80

output

50

input

1 2 10
11
15 7

output

7

Note

In the first example the person located at point 20 should take the key located at point 40 and
go with it to the office located at point 50. He spends 30 seconds.
The person located at point 100 can take the key located at point 80 and
go to the office with it. He spends 50seconds. Thus, after 50 seconds
everybody is in office with keys.

题目大意：n个人，k把钥匙，人取钥匙后到达目的地，问n个人全部到达后所需的最短时间
思路：二分，贪心

#include <cstdio>
#include <cstring>
#include <algorithm>
#define maxn 2005
typedef long long ll;
using namespace std;

int n, k, p;
int a[maxn], b[maxn];
bool check(ll x)
{
int pos = -1;
for (int i = 0; i < n; i++) {
while (pos < k) {
pos++;
if ((abs(a[i] - b[pos]) + abs(b[pos] - p)) <= x) break;
}
if (pos >= k) return false;
}
return true;
}
int main()
{
while (~scanf("%d%d%d", &n, &k, &p)) {
for (int i = 0; i < n; i++)
scanf("%d", &a[i]);
for (int i = 0; i < k; i++)
scanf("%d", &b[i]);
sort(a, a + n);
sort(b, b + k);
ll l = 0, r = 2e9, ans;
while (l <= r) {
ll mid = (r + l) / 2;
if (check(mid)) {
ans = mid;
r = mid - 1;
}
else l = mid + 1;
}
printf("%I64d\n", ans);
}
return 0;
}