ZOJ1062 Trees Made to Order

#include<iostream>

using namespace std;

long key;
int nodeNum;
long sum;
long f[30];
int temp;

void print(int nNum,int t)
{
int i;
int num=0;
int k;
for(i=0;i<nNum;i++){
num+=f[i]*f[nNum-i-1];
if(num>=t){
num-=f[i]*f[nNum-i-1];
break;
}
}
t=t-num;

if(i!=0){
cout<<"(";
k=t/f[nNum-i-1];
if(t%f[nNum-i-1]!=0)
k++;
print(i,k);
cout<<")";
}
cout<<"X";
if(nNum-i-1>0){
cout<<"(";
k=(t-1)%f[nNum-i-1]+1; //???很重要，直接用t%f[nNum-i-1]是错的。因为7%1=0，而6%1+1=1.
print(nNum-i-1,k);
cout<<")";
}
}

void calNodeNum()
{
int i;
sum=0;
for(i=1;;i++){
sum+=f[i];
if(sum>=key){
sum=sum-f[i];
break;
}
}
nodeNum=i;
}

void cal_f()
{
int i;
sum=0;
int t=1;
f[0]=1;

while(1){
for(i=0;i<t;i++)
f[t]+=f[i]*f[t-i-1];
sum+=f[t];
if(sum>=500000000)
break;
t++;
}
}

int main()
{
while(cin>>key && key!=0){

memset(f,0,sizeof(f));
cal_f();

calNodeNum();

temp=key-sum;

print(nodeNum,temp);

cout<<endl;
}
return 0;
}