求助，p2678```cpp
#include
using namespace std;
int l,n,m,a[50005];
int lleft,rright,mid=0;
bool check(int x)
{
int sum=0;
int now=0,i=0;
while(i<n+1)
{
i++;
//cout<<a[i]-a[now]<<endl;
if((a[i]-a[now])<x)
{
sum++;
}
else
{
now=i;
}
}
return sum>m;
}
int main()
{
cin>>l>>n>>m;
a[n+1]=l;
for(int i=1;i<=n;i++)
cin>>a[i];
lleft=1;rright=l;
long long ans;
while(lleft<=rright)
{
mid=(lleft+rright)/2;
//cout<<mid<<endl;
if(check(mid))
rright=mid-1;
else
{
ans=mid;
lleft=mid+1;
}
}
cout<<mid;
return 0;
}
