static int FindDigit(LongIntegerNumber divident, IList<int> divisorParts)
{
LongIntegerNumber divisor = new LongIntegerNumber(divisorParts, false);
if(divident == Zero || divisor > divident) {
return 0;
}
int dividentPart = ((divident.parts.Count == divisor.parts.Count) ? divident.parts.Last() : divident.parts.Last() * BaseFull + divident.parts[divident.parts.Count - 2]);
int divisorPart = divisor.parts.Last();
int lowDigit = Div(dividentPart, divisorPart + 1); //TODO optimize - no need to add 1 if divisor has zeros at the end
#if DEBUG
int checkCount = 0;
#endif
int topDigit = Div(dividentPart + 1, divisorPart);
int digit = Bisect(lowDigit, topDigit);
while(true) {
Number mult = divisor.Multiply(new LongIntegerNumber(new int[] { digit }, false));
LongIntegerNumber remain = (LongIntegerNumber)divident.Subtract(mult);
if(remain.isNegative) {
#if DEBUG
checkCount++;
#endif
topDigit = digit;
digit = Bisect(lowDigit, topDigit);
continue;
}
int comparisonResult = remain.Compare(divisor);
if(comparisonResult >= 0) {
#if DEBUG
checkCount++;
#endif
lowDigit = digit + 1;
digit = Bisect(lowDigit, topDigit);
continue;
}
break;
}
#if DEBUG
if(checkCount > 15)
throw new InvalidOperationException();
#endif
return digit;
}
