ants.cpp

#include<iostream>
 
using namespace std;
 
 
struct TAnt {
    int begin;
    int index;
    char smer;
    bool dead;
    int time;
};
 
int main( void ) {
    TAnt * Ants;
    int number, size, alive, last, prelast;
 
    last = prelast = 0;
    while ( cin >> size >> number ) {
        alive = number;
        Ants = new TAnt [number];
        for ( int i = 0; i < number; i++ ) {
            cin >> Ants [i] . index;
            Ants [i] . begin = Ants [i] . index;
            cin >> Ants [i] . smer;
            if ( ( Ants [i] . index == 0 && Ants [i] . smer == 'L' ) || ( Ants [i] . index == ( size - 1 ) && Ants [i] . smer == 'R' ) )
                Ants [i] . dead = true;
            else
                Ants [i] . dead = false;
 
            Ants [i] . time = 0;
        }
 
        if ( number == 1 )
        {
            if ( Ants [0] . index == 0 && Ants [0] . smer == 'L')
            {
                alive = 0;
                last = 0;
            }
 
            if ( Ants [0] . index == ( size - 1 ) && Ants [0] . smer == 'R' )
            {
                alive = 0;
                last = 0;
            }
        }
 
        while ( alive ) {
            for ( int i = 0; i < number; i++ ) {
 
 
                if ( Ants [i] . dead )
                {
                    continue;
                }
 
                if ( ( Ants [i] . index < 0 ) || ( Ants [i] . index >= size ) )
                    {
                        Ants [i] . dead = true;
                        if ( alive == number ) {
                            last = prelast = i;
                        }
                        else {
                            prelast = last;
                            last = i;
                        }
 
                        alive--;
                        continue;
                    }
 
                    if ( Ants [i] . smer == 'R' )
                        Ants [i] . index = Ants [i] . index + 1;
                    else
                        Ants [i] . index = Ants [i] . index - 1;
 
                    Ants [i] . time++;
 
                    for ( int j = 0; j < number; j++ ) {
                        if ( Ants [j] . dead )
                            continue;
 
                        if ( Ants [i] . index == Ants [j] . index ) {
                            if ( Ants [i] . smer == 'L' ) {
                                Ants [i] . smer = 'R';
                                Ants [j] . smer = 'L';
                            }
                            else {
                                Ants [i] . smer = 'L';
                                Ants [j] . smer = 'R';
                            }
                        }
                    }
                }
            }
 
            if ( prelast == last ) {
                cout << "The last ant will fall down in " << Ants [last] . time << " seconds - started at " << Ants [last] . begin << "." << endl;
            }
            else {
                cout << "The last ant will fall down in " << Ants [last] . time << " seconds - started at ";
                if ( Ants [last] . begin < Ants [prelast] . begin )
                    cout << Ants [last] . begin << " and " << Ants [prelast] . begin << "." << endl;
                else
                    cout << Ants [prelast] . begin << " and " << Ants [last] . begin << "." << endl;
        }
    }
 
    return ( 0 );
}