poj3258

#include <iostream>#include <cstdio>#include <algorithm>using namespace std;long long rock[50005],l,n,m;bool check(long long d){    int total=0,i=1,j=1;    while (i<n)    {        j=i+1;        while (rock[j]-rock[i]<d&&j<n)        {            total++;            j++;        }        i=j;    }    if (rock[n]-rock[n-1]<d) total++;    return total<=m;}int main(){   // freopen("in.txt","r",stdin);    cin>>l>>n>>m;    n+=2;    for (int i=2;i<=n-1;i++) cin>>rock[i];    rock[n]=l;    sort(rock+1,rock+n+1);    long long left=1,right=rock[n],mid;    while (right-left>1)    {        mid=(left+right)/2;        //cout<<left<<" "<<mid<<" "<<right<<" "<<check(mid)<<endl;        if (check(mid)) left=mid;else right=mid;    }    if (check(right)) cout<<right;else cout<<left;    return 0;}

题意：一些石头排成一条线，第一个和最后一个不能去掉，其余的共可以去掉m块，要使去掉后石头间距的最小值最大。