P1643: [Usaco2007 Oct]Bessie's Secret Pasture 贝茜的秘密草坪

呵呵呵呵呵，很水的DP，同时能够朴素枚举出来，这数据弱的 是 吃了尸米吧。。

 var n,i,j,k,l,ans:longint;
 begin
   readln(n);
   for i:= to trunc(sqrt(n)) do
     for j:= to trunc(sqrt(n)) do
       for k:= to trunc(sqrt(n)) do
         for l:= to trunc(sqrt(n)) do
           if i*i+j*j+k*k+l*l=n then inc(ans);
   writeln(ans);
 end.

然而这是正确的DP。

 var n,i,j,k:longint;
 a:array[..,..] of longint;
 begin
   readln(n);
   for i:= to trunc(sqrt(n)) do
     a[,i*i]:=;
   for i:= to  do
     for j:= to n do
       for k:= to trunc(sqrt(j)) do
         a[i,j]:=a[i,j]+a[i-,j-k*k];
   writeln(a[,n]);
 end.

(转载请注明出处：http://www.cnblogs.com/Kalenda/)