Charm Bracelet

Description

Bessie has gone to the mall's jewelry store and spies a charmbracelet. Of course, she'd like to fill it with the best charmspossible from the N (1 ≤ N ≤ 3,402) available charms.Each charm i in the supplied list has a weightW_i (1 ≤ W_i ≤ 400), a'desirability' factor D_i (1 ≤D_i ≤ 100), and can be used at most once. Bessiecan only support a charm bracelet whose weight is no more thanM (1 ≤ M ≤ 12,880).

Given that weight limit as a constraint and a list of the charmswith their weights and desirability rating, deduce the maximumpossible sum of ratings.

Input

* Line 1: Two space-separated integers: N andM
* Lines 2..N+1: Line i+1 describes charm iwith two space-separated integers: W_i andD_i

Output

* Line 1: A single integer that is the greatest sum of charmdesirabilities that can be achieved given the weightconstraints

Sample Input

4 61 42 63 122 7

Sample Output

23

Source

USACO 2007 December Silver

 

 

题意：裸的0-1背包问题。

考虑一个物品放或者不放，本来要滚动数组动规的，因为有可能多次取一物品，那么就可以从后往前修改f值就可以避免这种错误了。

 

AC CODE

programpku_3624;
var f:array[0..12880] of longint;
   n,c,i,j,v,w:longint;
begin
  readln(n,c);
  for i:=1 to n do
  begin readln(v,w);
    for j:=cdownto v do if f[j]<f[j-v]+w thenf[j]:=f[j-v]+w;
  end; writeln(f[c]);
end.