Terrible Sets
  
  
    | Time Limit: 1000MS |  | Memory Limit: 30000K | 
  
    | Total Submissions: 3017 |  | Accepted: 1561 | 
 
Description
Let N be the set of all natural numbers {0 , 1 , 2 
, . . . }, and R be the set of all real numbers. wi, hi for i = 1 . . . n are 
some elements in N, and w0 = 0. 
Define set B = {< x, y > | x, y ∈ 
R and there exists an index i > 0 such that 0 <= y <= hi 
,∑0<=j<=i-1wj <= x <= 
∑0<=j<=iwj} 
Again, define set S = {A| A = WH for some 
W , H ∈ R+ and there exists x0, y0 in N such that the set T = { 
< x , y > | x, y ∈ R and x0 <= x <= x0 +W and y0 <= y <= y0 + 
H} is contained in set B}. 
Your mission now. What is 
Max(S)? 
Wow, it looks like a terrible problem. Problems that appear to 
be terrible are sometimes actually easy. 
But for this one, believe me, 
it‘s difficult.
Input
The input consists of several test cases. For each 
case, n is given in a single line, and then followed by n lines, each containing 
wi and hi separated by a single space. The last line of the input is an single 
integer -1, indicating the end of input. You may assume that 1 <= n <= 
50000 and 
w1h1+w2h2+...+wnhn < 
109.
Output
Simply output Max(S) in a single line for each 
case.
Sample Input
3
1 2
3 4
1 2
3
3 4
1 2
3 4
-1
Sample Output
12
14
#include"iostream"
#include"stack"
#include"cstdio"
using namespace std;
struct abc
{
    int w;
    int h;
} data;
int main()
{
    int lasth,n,i,ans,curarea,totalw;
    while(cin>>n&&n!=-1)
    {
        stack<abc> s;
        ans=0;
        lasth=0;
        for(i=0;i<n;i++)
        {
            cin>>data.w>>data.h;
            if(data.h>=lasth)
            {
                lasth=data.h;
                s.push(data);
            }
            else
            {
                totalw=0;
                curarea=0;
                while(!s.empty()&&s.top().h>=data.h)
                {
                    totalw+=s.top().w;
                    curarea=totalw*s.top().h;
                    if(curarea>ans)
                       ans=curarea;
                    s.pop();  
                }
                totalw+=data.w;
                data.w=totalw;
                s.push(data);
            } 
        }
        totalw=0;
        curarea=0;
        while(!s.empty())
        {
            totalw+=s.top().w;
            curarea=totalw*s.top().h;
            if(curarea>ans)
                ans=curarea;
            s.pop();   
        }  
        cout<<ans<<endl;
    }
    return 0;
}
 
 
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Terrible Sets
原文:http://www.cnblogs.com/767355675hutaishi/p/3760929.html