*[topcoder]TheMatrix

http://community.topcoder.com/stat?c=problem_statement&pm=13035

矩阵棋盘的题，比较典型。可以定两条column夹住，然后上下扫，上下扫过程中有一点DP的东西，这样负责度是o(n^3)

#include <vector>

#include <algorithm>

#include <iostream>

using namespace std;



class TheMatrix {

public:

    int MaxArea(vector <string> board) {

        int N = board.size();

        int M = board[0].size();

        int maxArea = 1;

        // fix i, j column

        for (int i = 0; i < M; i++) {

            vector<char> row(N);

            for (int j = i; j < M; j++) {

                for (int k = 0; k < N; k++) {

                    if (j == i) {

                        row[k] = board[k][j];

                    } else {

                        if (board[k][j] == board[k][j - 1])

                            row[k] = 'X';

                    }

                }

                int maxLen = 0;

                int len = 0;

                for (int k = 0; k < N; k++) {

                    if (row[k] == 'X') {

                        len = 0;

                    } else if (k == 0) {

                        len = 1;

                    } else if (k > 0 && row[k] != row[k - 1]) {

                        len++;

                    } else {

                        len = 1;

                    }

                    maxLen = max(len, maxLen);

                }

                int area = maxLen * (j - i + 1);

                maxArea = max(area, maxArea);

            }

        }

        return maxArea;

    }

};