//must clone self so for deep cloning
public object Clone()
{
CharMapper clone = new CharMapper(0);
clone.count = this.count;
clone.finalCount = this.finalCount;
clone.indexes = this.indexes;
return(clone);
}
private string MapCharacters(string variation)
{
var result = new StringBuilder(variation);
for (var i = 0; i < result.Length; i++)
{
if (CharMapper.TryGetLetter(variation[i], out var convertedChar))
{
result[i] = convertedChar;
}
}
return(result.ToString());
}
static string reverseShuffleMerge(string s, string t)
{
//create map of all characters, their counts, and indexes
Dictionary <char, CharMapper> charMap = new Dictionary <char, CharMapper>();
for (int i = 0; i < s.Length; i++)
{
char c = s[i];
if (!charMap.ContainsKey(c))
{
charMap[c] = new CharMapper(i);
}
else
{
charMap[c].count++;
charMap[c].indexes.Add(i);
}
}
//divide each count in the dictionary by 2 to get character counts for A
List <char> keys = new List <char>(charMap.Keys);
List <char> ListChars = new List <char>();
foreach (char c in keys)
{
charMap[c].finalCount = charMap[c].count / 2;
for (int i = 0; i < charMap[c].finalCount; i++)
{
ListChars.Add(c);
}
}
//create an ordered char array to show alphebetic hierarchy of letters to encounter
char[] orderedChars = ListChars.ToArray();
Array.Sort(orderedChars);
//create ordered distinct list
// char[] orderdistinctchars = ListChars.Distinct().ToArray();
// Array.Sort(orderdistinctchars);
//instantiate result string
string result = "";
int strLength = s.Length / 2;
//start iterating backwards
for (int i = s.Length - 1; i >= 0; i--)
{
char c = s[i];
//did we encounter the best possible character, if so add it and remove that character from order array
//and from dictionary of needed character counts
if (c == orderedChars[0])
{
result += c;
orderedChars = orderedChars.Skip(1).ToArray();
charMap[c].count -= 1;
charMap[c].finalCount -= 1;
}
//is this character unskippable?
//if so we need to add it regardless, and remove it from order array
else if (charMap[c].count == charMap[c].finalCount)
{
result += c;
charMap[c].count -= 1;
charMap[c].finalCount -= 1;
int numidx = Array.IndexOf(orderedChars, c);
orderedChars = orderedChars.Where((val, idx) => idx != numidx).ToArray();
}
//is this character skippable at first glance?
//are there more characters of this string left than we need in the final string
else if (charMap[c].count > charMap[c].finalCount && charMap[c].finalCount != 0)
{
//next idx of best character
int nextBestIdx = charMap[orderedChars[0]].indexes.Where(idx => idx < i).Max();
//next unskippable idx
int nextUnskippableIdx = -1;
//iterate from current point till next best
int j = i - 1;
//*************************************THIS IS THE IMPORTANT PART TO LOOK AT************************
//i want to copy the mapping object here, so i can manipulate it to simulate characters being skipped
//COPY ONLY SHALLOW COPIES THE DICTIONARY, MEANING THE CHARMAPPER OBJECTS ARE STILL REFERENCING THE ORGIONAL
// Dictionary<char, CharMapper> copy = new Dictionary<char, CharMapper>(charMap);
//DEEP CLONE, charMapper Objects are now independant and not a reference
Dictionary <char, CharMapper> clone = charMap.ToDictionary(kv => kv.Key, kv => kv.Value.Clone() as CharMapper);
while (j != nextBestIdx)
{
char charToCheck = s[j];
//if there are only enough left to fulfill final count then its unskippable
if (clone[charToCheck].count == clone[charToCheck].finalCount)
{
nextUnskippableIdx = j;
break;
}
clone[charToCheck].count--;
j--;
}
//*************************************THIS IS THE IMPORTANT PART TO LOOK AT************************
j = i - 1;
bool breakFlag = false;
//for tracking purposes
char nextUnskippableChar = nextUnskippableIdx != -1 ? s[nextUnskippableIdx] : 'z';
//if the next best is closer than unskippable, or current character is worse than next unskippable
//THERE IS A CHARACTER THAT WILL BECOME UNSKIPPABLE BEFORE NEXT BEST, AND THIS CHARACTER IS BETTER THAN IT
//THE REASON ITS NOT FOUND IS THAT THERE ARE MULTIPLE INSTANCES WHAT WILL BECOME THE NEXT UNSKIPPABLE (SO ITS NOT THINKING THAT IT IS UNSKIPPABLE)
if (nextBestIdx >= nextUnskippableIdx || c > nextUnskippableChar)
{
breakFlag = true;
}
else
{
//we want to look for a better character than current character before we hit the idx of next best option or an unskippable
while (j > nextBestIdx && j > nextUnskippableIdx)
{
char charToCheck = s[j];
//is this character better choice? if yes we can stop looking and skip this character
if (charToCheck < c && charMap[charToCheck].finalCount > 0)
{
breakFlag = true;
break;
}
j--;
}
}
//we've determiend there are better characters before next best or next unskippable, so lets skip this one
if (breakFlag)
{
charMap[c].count--;
}
//there are not better characters bef
else
{
result += c;
charMap[c].count -= 1;
charMap[c].finalCount -= 1;
int numidx = Array.IndexOf(orderedChars, c);
orderedChars = orderedChars.Where((val, idx) => idx != numidx).ToArray();
}
//********************************************************borken part */
}
// the only condition left is that we found lexagraphical better character that we don't need any more of
else
{
charMap[c].count--;
}
//if we've completd the string, stop looping
if (result.Length == strLength)
{
break;
}
}
return(result);
}
