题目2 : Disk Storage

Disk_Storage.cpp

#include <iostream>
#include <queue>
#include <string>
#include <vector>
#include <algorithm>

#include <cmath>
#include <ctime>
#include <cstdio>
#include <cstring>
#include <cstdlib>

using namespace std;
typedef vector<int>::iterator IT;
vector<int> disks;
vector<bool> flag;
int M;

int maxdisk(int H,int R,int x,int counts){
    if(H==0||counts>=disks.size())return 0;
    int maxval=0;
    IT it= upper_bound(disks.begin(), disks.end(), min(R,x));
    for(IT i=disks.begin();i!=it;i++){
        int loc=int(i-disks.begin());
        if (flag[loc]) {
            flag[loc]=false;
            maxval=max(maxval,1+maxdisk(H-1, R+1, *i+M,counts+1));
            flag[loc]=true;
        }
    }
    return maxval;
}


int main()
{
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
#endif
    int N,R,H;
    cin>>N>>M>>H>>R;
    int disk;
    while(N--){
        cin>>disk;
        disks.push_back(disk);
    }
    flag.resize(disks.size());
    fill(flag.begin(),flag.end(),true);
    cout<<maxdisk(H,R,R,0);
}

http://hihocoder.com/contest/mstest2015jan1/problem/2

题目2 : Disk Storage
时间限制:10000ms
单点时限:1000ms
内存限制:256MB
描述
1.png

Little Hi and Little Ho have a disk storage. The storage's shape is a truncated cone of height H. R+H is radius of top circle and R is radius of base circle.
Little Ho buys N disks today. Every disk is a cylinder of height 1. Little Ho wants to put these disk into the storage under below constraints:

1. Every disk is placed horizontally. Its axis must coincide with the axis of storage.
2. Every disk is either place on the bottom surface or on another disk.
3. Between two neighboring disks in the storage, the upper one's radius minus the lower one's radius must be less than or equal to M.

Little Ho wants to know how many disks he can put in the storage at most.

输入
Input contains only one testcase.
The first line contains 4 integers: N(1 <= N <= 100000), M, H, R(1 <= M, R, H <= 100000000).
The second line contains N integers, each number prepresenting the radius of a disk. Each radius is no more than 100000000.

输出
Output the maximum possible number of disks can be put into the storage.

样例输入
5 1 10 3
1 3 4 5 10
样例输出
4

复杂度这么高，果然TLE= =。。