Pascal(fpc 3.0.2) 解法, 执行用时: 33ms, 内存消耗: 620K, 提交时间: 2019-07-04 11:45:36

var
 n,m,k,l,r,max,mid,sum,ans:int64;
 i:longint;
 a:array[0..100001] of int64;
procedure kuaipai(l,r:longint);
var
 i,j,k,s:longint;
begin
 i:=l;
 j:=r;
 k:=a[(i+j) div 2];
 repeat
  while a[i]<k do
   i:=i+1;
  while a[j]>k do
   j:=j-1;
  if i<=j then begin
                s:=a[i];
                a[i]:=a[j];
                a[j]:=s;
                i:=i+1;
                j:=j-1;
               end;
 until i>j;
 if i<r then kuaipai(i,r);
 if l<j then kuaipai(l,j);
end;
function check(x:longint):boolean;
var
 j,cnt:int64;
 i:longint;
begin
 j:=0;
 cnt:=0;
 for i:=1 to n do
  begin
   if(j+x>a[i])then cnt:=cnt+1
               else j:=a[i];
  end;
 if cnt>m then exit(false)
          else exit(true);
end;
begin
  readln(k,n,m);
  for i:=1 to n do
    begin
      readln(a[i]);
    end;
  n:=n+1;
  a[n]:=k;
  kuaipai(1,n);
  l:=0;
  r:=k;
  while l<=r do
    begin
      mid:=(l+r) div 2;
      if check(mid) then begin
                          l:=mid+1;
                          if mid>ans then ans:=mid;
                         end
                    else r:=mid-1;
    end;
  writeln(ans);
end.

C++11(clang++ 3.9) 解法, 执行用时: 41ms, 内存消耗: 536K, 提交时间: 2020-01-31 19:14:42

#include<bits/stdc++.h>
using namespace std;
int n,m,w[50005];
bool ok(int s)
{
	int tm=m,now=1,temp=2;
	while(now<=n+1&&tm>=0)
	{
		if(w[temp]-w[now]<s)tm--;
		else now=temp;
		temp++;
	}
	if(tm<0)return 0;
	return 1;
}
int main()
{
	int d;cin>>d>>n>>m;w[n+2]=d;
	for(int i=2;i<=n+1;i++)cin>>w[i];
    sort(w+1,w+n+3);
	int l=1,r=d;
	while(l<r-1)
	{
		int mid=(l+r)>>1;
		if(ok(mid))l=mid;
		else r=mid-1;
	}
	if(ok(r))cout<<r;
	else cout<<l;
    return 0;
}