POJ3132

题意:求将N分成K个不同质数的和的方案数.

分析:筛法,然后直接背包之~~.

code:

const MAX=1200;
      maxn=1200;
      maxk=15;
var   Prime:array[0..MAX] of longint;
      P:array[0..MAX] of boolean;
      f:array[0..maxn,0..maxk] of longint;
      size,n,k,i,j,o,tmp:longint;

      procedure GetPrime;
      begin
            size:=0;
            fillchar(P,sizeof(P),0);
            for i:=2 to MAX do
            begin
                  if not P[i] then
                  begin
                  	    inc(size);
                        prime[size]:=i;
                  end;
                  j:=1;
                  while (j<=size)and(prime[j]*i<MAX) do
                  begin
                        P[i*prime[j]]:=true;
                        if i mod prime[j]=0 then break;
                        inc(j);
                  end;
            end;
      end;

begin
      GetPrime;
      while not seekeof do
      begin
            readln(n,k);
            if n+k=0 then break;
            tmp:=0;
            while prime[tmp]<=n do inc(tmp); dec(tmp);
            fillchar(f,sizeof(f),0);
            f[0,0]:=1;
            for o:=1 to tmp do
               for i:=n downto prime[o] do
                  for j:=1 to k do
                  f[i,j]:=f[i,j]+f[i-prime[o],j-1];
            writeln(f[n,k]);
      end;
end.