最大联通子数组

返回一个二维整数数组中最大联通子数组的和。

要求：

输入一个二维整形数组，数组里有正数也有负数。

求所有子数组的和的最大值。下面是给的示例图：

 

队员：王楗  http://home.cnblogs.com/u/wangjianly/

#include <iostream>
#include<fstream>
#include <time.h>
using namespace std;

#define m 100
#define n 100

void main()
{
    int a[m][n] = { 0 }, b[m][n] = { 0 };            //判断联通性，0为未选中，1为选中,2为连通
    bool flg = 0;                              //判断是否有1存在，存在为O。
    int sum = 0;                               //最后和
    int M, N;
    ofstream outfile;
    outfile.open("intput.txt");
    if (!outfile)
        {
         cerr << "OPEN ERROR!" << endl;
         exit(0);
        }
    cout << "输入数组的行数和列数：" << endl;
    cin >> M;
    outfile << M << endl;
    cin >> N;
    outfile << N << endl;
    srand(unsigned((int)time(0)));

    for (int i = 0; i < M; i++)
    {
        for (int j = 0; j < N; j++)
        {
            a[i][j] = rand() % 50 - 20;
            cout << a[i][j] << "	";
            outfile << a[i][j] << "	";
            if (a[i][j] >= 0)
            {
                b[i][j] = 1;
            }
        }
        cout << endl;
        outfile <<endl;
    }
    cout << endl;

    for (int i = 0; i < M; i++)
    {
        for (int j = 0; j < N; j++)
        {
            if (b[i][j] == 1)
            {
                if (a[i + 1][j] + a[i][j] > 0 && b[i + 1][j] == 0)
                {
                    b[i + 1][j] = 2;
                }
                if (a[i - 1][j] + a[i][j] > 0 && b[i - 1][j] == 0)
                {
                    b[i - 1][j] = 2;
                }
                if (a[i][j - 1] + a[i][j] > 0 && b[i][j - 1] == 0)
                {
                    b[i][j - 1] = 2;
                }
                if (a[i][j + 1] + a[i][j] > 0 && b[i][j + 1] == 0)
                {
                    b[i][j + 1] = 2;
                }
            }
        }
    }

    for (int i = 0; i < M; i++)
    {
        for (int j = 0; j < N; j++)
        {
            flg = 0;
            if (b[i][j] != 0 && a[i][j] < 0)
            {
                b[i][j] = 0;
                for (int k = 0; k < M; k++)
                {
                    for (int l = 0; l < N; l++)
                    {
                        if (b[k][l] != 0)
                        {
                            if ((b[k + 1][l] <= 0 || b[k + 1][l] > 2) && (b[k - 1][l] <= 0 || b[k - 1][l] > 2) && (b[k][l + 1] <= 0 || b[k][l + 1] > 2) && (b[k][l - 1] <= 0 || b[k][l - 1] > 2))
                            {
                                flg = 1;
                            }
                        }
                    }
                }
                if (flg)
                {
                    b[i][j] = 2;
                }
            }
        }
    }

    for (int i = 0; i < M; i++)
    {
        for (int j = 0; j < N; j++)
        {
            if (b[i][j] != 0)
            {
                cout << a[i][j] << "	";
                sum += a[i][j];
            }
            else
            {
                cout << "**" << "	";
            }
        }
        cout << endl;
    }
    cout << "sum = " << sum << endl;
    outfile << "sum = " << sum << endl;
    outfile.close();
}

运行结果：

测试数据：3*4

、

测试数据4*4：