BZOJ1024: [SCOI2009]生日快乐

这题上来看以为是dp，其实是搜索，我顺便把搜索的路径存下来了(这样才看明白样例......)。 —— by VANE

#include<bits/stdc++.h>
#define MP make_pair
#define xx first
#define yy second
using namespace std;
double a,b;
int n;
typedef pair<pair<double,double>,int> pa;
map<pa,pa>pre;
double dfs(double x,double y,int k)
{
    if(k==1)
    return max(x/y,y/x);
    double ans=1e9;
    for(int i=1;i<=k/2;++i)
    {
        double nx=x/k*i,ny=y/k*i;
        double t=max(dfs(nx,y,i),dfs(x-nx,y,k-i));
        if(t<ans)
        {
            ans=t;
            pre[MP(MP(x,y),k)]=MP(MP(nx,y),i);
        }
        t=max(dfs(x,ny,i),dfs(x,y-ny,k-i));
        if(t<ans)
        {
            ans=t;
            pre[MP(MP(x,y),k)]=MP(MP(x,ny),i);
        }
    }
    return ans;
}
void print(double x,double y,int k)
{
    double na,nb;
    int nn;
    if(k<=1) return;
    pa p=MP(MP(x,y),k);
    na=pre[p].xx.xx;
    nb=pre[p].xx.yy;
    nn=pre[p].yy;
    printf("%.2lf %.2lf %d
",na,nb,nn);
    print(na,nb,nn);
    if(nb==y)
    {
        printf("%.2lf %.2lf %d
",x-na,nb,k-nn);
        print(x-na,nb,k-nn);
    }
    else 
    {
        printf("%.2lf %.2lf %d
",x,y-nb,k-nn);
        print(na,y-nb,k-nn);
    }
}
int main()
{
    scanf("%lf%lf%d",&a,&b,&n);
    printf("%.6lf
",dfs(a,b,n));
    print(a,b,n);
}