Good time of day.
I constantly get WA on test #6. Does anybody know why may this happen?
Here's my code, seems to give correct answers for any correct test found in discussions:

#include <stdio.h>
#include <iostream>
#include <map>

using namespace std;

typedef unsigned int uint;

const uint MAX_N = 5000;
const bool COLOR_BLACK = false;
const bool COLOR_WHITE = true;

typedef pair <uint, bool> LinePair;
typedef map<uint, LinePair> TLines;

TLines lines;

void paint(uint c, uint d, const bool clr)
{
    if (c == d)
        return;
    uint a, b;
    bool c2;
    if (lines.empty())
    {
        lines[c] = LinePair(d, clr);
        return;
    }

    TLines::iterator i = lines.begin();
    //пропускаем все отрезки, что левее нашего и не накладываются на него
    while (c > (i->second).first) ++i;
    //работаем с накладывающимися отрезками
    while ((d >= i->first) && (i != lines.end()))
    {
        //для удобства написания
        a = i->first;
        b = (i->second).first;
        c2 = (i->second).second;
        if (a >= c)
        {
            if (d >= b)
            {
                lines.erase(i);
            }
            else if (clr == c2)
            {
                d = b;
                lines.erase(i);
            }
            else
            {
                lines.erase(i);
                lines[d] = LinePair(b, c2);
            }
        }
        else
        {
            if (d >= b)
            {
                if (clr == c2)
                {
                    c = a;
                    lines.erase(i);
                }
                else
                {
                    (i->second).first = c;
                }
            }
            else if (clr == c2)
            {
                c = a;
                d = b;
            }
            else
            {
                (i->second).first = c;
                lines[d] = LinePair(b, c2);
            }
        }
        ++i;
    }
    //собственно добавление заданного отрезка
    lines[c] = LinePair(d, clr);
    return;
}

int main()
{
    uint n, b, e;
    char ch;
    bool clr;
#ifndef ONLINE_JUDGE
    freopen("input.txt", "rt", stdin);
    //freopen("output.txt", "wt", stdout);
#endif
    lines.clear();
    paint(0, 1e+9, COLOR_WHITE);
    cin >> n;
    for (uint i = 0; i < n; i++)
    {
        cin >> b >> e >> ch;
        if (ch == 'b')
            clr = COLOR_BLACK;
        else
            clr = COLOR_WHITE;
        paint(b, e, clr);
    }
    TLines::const_iterator maxLine;
    uint max = 0;
    for (TLines::const_iterator i = lines.begin(); i != lines.end(); ++i)
    {
        if (((i->second).second == COLOR_WHITE) && ((i->second).first - i->first > max))
        {
            max = (i->second).first - i->first;
            maxLine = i;
        }
#ifndef ONLINE_JUDGE
        cout << i->first << '\t' << (i->second).first << '\t' << (i->second).second << endl;
#endif
    }
    cout << maxLine->first << " " << (maxLine->second).first << endl;
    return 0;
}

Edited by author 05.01.2011 03:29

I've got AC. I just needed not to use iterator after erasing it. But the solution is far from optimal, I'm gonna rewrite it.

AC

#include <stdio.h>
#include <iostream>
#include <map>

using namespace std;

typedef unsigned int uint;

const uint MAX_N = 5000;
const bool COLOR_BLACK = false;
const bool COLOR_WHITE = true;

typedef pair <uint, bool> LinePair;
typedef map<uint, LinePair> TLines;

TLines lines;

void paint(uint c, uint d, const bool clr)
{
    if (c == d)
        return;
    uint a, b;
    bool c2;
    if (lines.empty())
    {
        lines[c] = LinePair(d, clr);
        return;
    }

    TLines::iterator i = lines.begin();
    //пропускаем все отрезки, что левее нашего и не накладываются на него
    while (c > (i->second).first) ++i;
    //работаем с накладывающимися отрезками
    while ((d >= i->first) && (i != lines.end()))
    {
        //для удобства написания
        a = i->first;
        b = (i->second).first;
        c2 = (i->second).second;
        if (a >= c)
        {
            if (d >= b)
            {
                i = lines.erase(i);
            }
            else if (clr == c2)
            {
                d = b;
                i = lines.erase(i);
            }
            else
            {
                i = lines.erase(i);
                lines[d] = LinePair(b, c2);
            }
        }
        else
        {
            if (d >= b)
            {
                if (clr == c2)
                {
                    c = a;
                    i = lines.erase(i);
                }
                else
                {
                    (i->second).first = c;
                    i++;

                }
            }
            else if (clr == c2)
            {
                c = a;
                d = b;
                i++;
            }
            else
            {
                (i->second).first = c;
                lines[d] = LinePair(b, c2);
                i++;
            }
        }
    }
    //собственно добавление заданного отрезка
    lines[c] = LinePair(d, clr);
    return;
}

int main()
{
    uint n, b, e;
    char ch;
    bool clr;
#ifndef ONLINE_JUDGE
    freopen("input.txt", "rt", stdin);
    //freopen("output.txt", "wt", stdout);
#endif
    lines.clear();
    paint(0, 1e+9, COLOR_WHITE);
    cin >> n;
    for (uint i = 0; i < n; i++)
    {
        cin >> b >> e >> ch;
        if (ch == 'b')
            clr = COLOR_BLACK;
        else
            clr = COLOR_WHITE;
        paint(b, e, clr);
    }
    TLines::const_iterator maxLine;
    uint max = 0;
    for (TLines::const_iterator i = lines.begin(); i != lines.end(); ++i)
    {
        if (((i->second).second == COLOR_WHITE) && ((i->second).first - i->first > max))
        {
            max = (i->second).first - i->first;
            maxLine = i;
        }
#ifndef ONLINE_JUDGE
        cout << i->first << '\t' << (i->second).first << '\t' << (i->second).second << endl;
#endif
    }
    cout << maxLine->first << " " << (maxLine->second).first << endl;
    return 0;
}