bzoj 2748 DP

　　比较裸的背包，w[i][j]代表到第I个操作的时候音量j能不能达到，然后转移就行了。

　

/**************************************************************
    Problem:
    User: BLADEVIL
    Language: Pascal
    Result: Accepted
    Time: ms
    Memory: kb
****************************************************************/

//By BLADEVIL
var
    n, s, h                     :longint;
    i, j                        :longint;
    v                           :array[..] of longint;
    w                           :array[..,..] of boolean;

begin
    read(n,s,h);
    for i:= to n do read(v[i]);

    fillchar(w,sizeof(w),false);
    w[][s]:=true;
    for i:= to n do
        for j:= to h do
        begin
            if j-v[i]>= then w[i][j]:=w[i][j] or w[i-][j-v[i]];
            if j+v[i]<=h then w[i][j]:=w[i][j] or w[i-][j+v[i]];
        end;
    for i:=h downto  do if w[n][i] then break;
    if (i=) and (not w[n][i]) then writeln(-) else writeln(i);
end.