C / C++ / MFC

LiYS wrote:

you should find the first occurrence of a character that also appeared foremost in the string

// VanillaConsole.cpp : Defines the entry point for the console application.
//
 
#include "stdafx.h"
#include <iostream>
using namespace std;
 
int main()
{
	const char *pstr = "aabbccddeffghijk";
 
	for (unsigned int i=1; pstr[i]!=0; ++i)
	{
		if (pstr[i]!=pstr[i-1] && pstr[i]!=pstr[i+1])
		{
			cout << "First unique character: " << pstr[i] << endl;
			return 0;
		}
	}
 
	cout << "No unique characters." << endl;
 
	return 0;
}

TCHAR findfirstuniquechar_sorted (TCHAR *sz)
{
    if (!sz) return 0;

    // loop through while safe
    for (int n = 0; sz [n]; n++)
    {
        if (sz [n] == sz [n+1]) // we're the same as the one after
            continue;
        if ( (n > 0) && (sz [n] == sz [n-1])) // we're the same as the one before!
            continue;

        // found one that's different from either side.
        return sz [n];
    }
    return 0; // none found.
}

TCHAR findfirstuniquechar_unsorted (TCHAR *sz)
{
	if (!sz)
		return 0;

; This line posts badly - it should be CMap less than TCHAR, TCHAR and, int, int and greater-then CharMap; hope that made sense...   pre bug reported.
	CMap<TCHAR, TCHAR &, int, int &> CharMap;
	int nPos;
	int nCharPos;

	// One pass through string.
	for (nPos = 0; sz [nPos]; nPos++)
	{
		if (CharMap.Lookup (sz [nPos], nCharPos))
		{
			// char already used, so signal is as not-counting-anymore
			CharMap [sz[nPos]] = -1;
		}
		else
		{
			// New one!
			CharMap [sz[nPos]] = nPos;
		}
	}

	// Now all chars are account for, look for the char with the lowest <= 0 position.
	POSITION pos = CharMap.GetStartPosition ();
	nPos = -1;
	TCHAR c, cFirst = 0;
	while (pos)
	{
		CharMap.GetNextAssoc (pos, c, nCharPos);
		if (nCharPos < 0) // not a unique char.
			continue;

		if ( (nPos == -1) || (nCharPos < nPos)) // is this the earliest, or the first unique one we've mapped?
		{
			cFirst = c;
			nPos = nCharPos;
		}
	}
	
	return cFirst; // either first unique, or 0;
}