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  • poj2082 Terrible Sets(单调栈)

    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

    Source

    Shanghai 2004 Preliminary
     
     
    刚做了poj2559,这题只是每个矩形有宽度了。
     1 program rrr(input,output);
     2 var
     3   h,l,r,q,sum:array[0..50050]of longint;
     4   n,i,t,ans,w:longint;
     5 function max(a,b:longint):longint;
     6 begin
     7    if a>b then exit(a) else exit(b);
     8 end;
     9 begin
    10    assign(input,'r.in');assign(output,'r.out');reset(input);rewrite(output);
    11    while true do
    12       begin
    13          readln(n);if n=-1 then break;
    14          sum[0]:=0;
    15          for i:=1 to n do begin readln(w,h[i]);sum[i]:=sum[i-1]+w; end;
    16          t:=0;q[0]:=0;
    17          for i:=1 to n do
    18             begin
    19                while (t>0) and (h[i]<=h[q[t]]) do dec(t);
    20                l[i]:=q[t];
    21                inc(t);q[t]:=i;
    22             end;
    23          t:=0;q[0]:=n+1;
    24          for i:=n downto 1 do
    25             begin
    26                while (t>0) and (h[i]<=h[q[t]]) do dec(t);
    27                r[i]:=q[t];
    28                inc(t);q[t]:=i;
    29             end;
    30          ans:=0;
    31          for i:=1 to n do ans:=max(ans,h[i]*(sum[r[i]-1]-sum[l[i]]));
    32          writeln(ans);
    33       end;
    34    close(input);close(output);
    35 end.
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  • 原文地址:https://www.cnblogs.com/Currier/p/6686596.html
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