int solve_104()
{
Pair num0(1, 1), num1(1, 1);
int result = 2;
#ifdef ApproachOne
const Pair::Number Max = (~((Pair::Number)0)) / 10; // UINT64_MAX / 10
for(; !Pandigital(num1); ++result)
{
// It's easy to handle the low-9 digits.
Pair::Number t_low = num1.low;
num1.low = (num1.low + num0.low) % Sieve;
num0.low = t_low;
Pair::Number t_high = num1.high + num0.high;
// dig_count(x) + dig_count(y) <= 1 + max(dig_count(x), dig_count(y)).
if(t_high > Max)
{
// num1.high is a little too big, shrink it.
t_high /= 10;
num1.high /= 10;
}
num0.high = num1.high;
num1.high = t_high;
}
#else // Another approach, amazing.
for(; ; )
{
++result;
// It's easy to handle the low-9 digits.
Pair::Number t_low = num1.low;
num1.low = (num1.low + num0.low) % Sieve;
num0.low = t_low;
if(PanHelper(num1.low))
{
// F(n) = ((phi ^ n) / sqrt(5.0)).
// phi = (1 + sqrt(5)) / 2, 黄金分割.
// 设 l_10 = log10(F(n))
// 然后计算
// pow(10, 8.0 + (l_10的小数部分)).
// 因为是10的乘方,所以非000项都是由10的小数次方产生的.
// 当n足够大时,这个值非常接近F(n).
// log(pi) = 0.20898764024997873.
// log(sqrt(5)) = 0.3494850021680094.
const double t = (result * 0.20898764024997873 - 0.3494850021680094);
num1.high = (Pair::Number)pow(10, t - (Pair::Number)t + 8.0);
if(PanHelper(num1.high))
break;
}
}
#endif
return result;
}
//*******************************************************************
// The following visitor functions deal with detecting Z's in the
// logic, stripping the Z's out and creating an __en signal and its
// logic.
//*******************************************************************
virtual void visit(AstPull* nodep, AstNUser*) {
// replace any pullup/pulldowns with assignw logic and an __en
// signal just like it is any other tristate signal. The only
// difference is that the user2() variable on the __en signal
// will be given a pull direction--i.e. pulldown=1, pullup=2.
// This will signal the driver exansion logic to put a default
// pullup or pulldown state on the tristate bus under the high-Z
// condition when no one is driving the bus. Given the complexity
// of merging tristate drivers at any level, the current limitation
// of this implementation is that a pullup/down gets applied
// to all bits of a bus and a bus cannot have drivers in opposite
// directions on indvidual pins.
AstNode* outp = nodep->lhsp()->unlinkFrBack();;
AstVarRef* outrefp = NULL;
int width=-1;
if (outp->castVarRef()) {
outrefp = outp->castVarRef();
} else if (outp->castSel()) {
outrefp = outp->castSel()->fromp()->castVarRef();
width = outp->castSel()->widthConst();
} else {
nodep->v3error("Can't find LHS varref");
}
outrefp->lvalue(true);
AstVar* varp = outrefp->varp();
if (width==-1) width=varp->width();
V3Number num0 (nodep->fileline(), width);
num0.setAllBits0();
V3Number num1 (nodep->fileline(), width);
num1.setAllBits1();
AstConst* enrhsp = new AstConst(nodep->fileline(), num0);
AstVar* enp = createEnableVar(outp, outrefp, enrhsp, width, "pull");
enp->user2(nodep->direction()+1); // record the pull direction
AstAssignW* newassp = new AstAssignW(nodep->fileline(), outp,
new AstConst(nodep->fileline(), nodep->direction() ? num1 : num0));
nodep->replaceWith(newassp);
nodep->deleteTree(); nodep=NULL;
newassp->iterateChildren(*this);
}
