SRM453.5 Div1 Easy(250) MazeMaker - kusano

１日勘違いしてて、参加し損ねた。ぐぬぬ。
#include <vector>
#include <string>

using namespace std;

class MazeMaker
{
public:
    int longestPath( vector<string> maze, int startRow, int startCol,
                     vector<int> moveRow, vector<int> moveCol );
};

int MazeMaker::longestPath( vector<string> maze,
    int startRow, int startCol, vector<int> moveRow, vector<int> moveCol )
{
    int w = (int)maze[0].size();
    int h = (int)maze.size();

    vector<vector<int> > step( h, vector<int>( w, INT_MAX ) );
    step[startRow][startCol] = 0;

    for ( int s=0; ; s++ )
    {
        bool update = false;

        for ( int y=0; y<h; y++ )
        for ( int x=0; x<w; x++ )
        if ( step[y][x] == s )
        {
            for ( int i=0; i<(int)moveRow.size(); i++ )
            {
                int tx = x + moveCol[i];
                int ty = y + moveRow[i];

                if ( 0 <= tx  &&  tx < w  &&
                     0 <= ty  &&  ty < h  &&
                     maze[ty][tx] == '.'  &&
                     step[ty][tx] == INT_MAX )
                {
                    step[ty][tx] = s + 1;
                    update = true;
                }
            }
        }

        if ( ! update )
            break;
    }

    int answer = 0;
    for ( int y=0; y<h; y++ )
    for ( int x=0; x<w; x++ )
        if ( maze[y][x] == '.' )
            answer = max( answer, step[y][x] );

    return answer==INT_MAX ? -1 : answer;
}