计算水池数目

原题目链接：原题目

采用广度优先算法来做

为了简单起见，不从标准输入读取数据，数据在代码中指定

代码如下：

#include <iostream>
#include <list>
using namespace std;
#define COLUMN_NUMBER 5
#define ROW_NUMBER 5

int get_count(const int (*data)[COLUMN_NUMBER]);

struct Point {
    int x;
    int y;
    Point(int x,int y)
    {
        this->x = x;
        this->y = y;
    }
    Point(){}

};

int main()
{
    int data[ROW_NUMBER][COLUMN_NUMBER] = {{1,1,1,1,0},
                                          {0,0,1,0,1},
                                          {0,0,0,0,0},
                                          {1,1,1,0,0},
                                          {0,0,1,1,1}};
    int count = get_count(data);
    cout << "count = " << count << endl;
    return 0;
}


int get_count(const int (*data)[COLUMN_NUMBER])
{
    int count = 0;
    int is_travelled[ROW_NUMBER][COLUMN_NUMBER] = {0};

    for(int i = 0;i < ROW_NUMBER;++i)
    {
        for(int j = 0;j < COLUMN_NUMBER;++j)
        {
            //if it is a pool and is has not been travelled
            if(1 == data[i][j] && 0 == is_travelled[i][j])
            {
                ++count;

                is_travelled[i][j] = 1;//make it been travelled
                list<Point> vec;
                Point p(i,j);
                vec.push_back(p);
                while(!vec.empty())
                {
                    Point current_point = vec.front();//get the first element
                    vec.erase(vec.begin());//delete the first element
                    //get the four neighor coordinates
                    int left_top_x = current_point.x == 0 ? 0 : current_point.x -1 ;
                    int left_top_y = current_point.y == 0 ? 0 : current_point.y - 1;
                    int right_bottom_x = current_point.x == ROW_NUMBER - 1 ? ROW_NUMBER - 1 : current_point.x + 1;
                    int right_bottom_y = current_point.y == COLUMN_NUMBER - 1 ? COLUMN_NUMBER - 1 : current_point.y + 1;

                    Point vertex[4];
                    vertex[0] = Point(left_top_x,current_point.y);
                    vertex[1] = Point(right_bottom_x,current_point.y);
                    vertex[2] = Point(current_point.x,left_top_y);
                    vertex[3] = Point(current_point.x,right_bottom_y);

                    for(int i = 0; i < 4;++i)
                    {
                        Point _p = vertex[i];
                        if(0 == is_travelled[_p.x][_p.y] && 1 == data[_p.x][_p.y])
                            vec.push_back(_p);
                        is_travelled[_p.x][_p.y] = 1;
                    }
                }
            }
        }
    }

    return count;

}