POJ 1069 The Bermuda Triangle

一道考数据结构的好题

要利用好斜坐标系来表示各点，原理网上都有

题目连接。。。

自己闲着无聊用冗杂的代码压时间，居然压到32ms

#include <iostream>
#include <algorithm>
using namespace std;

#define CHOICE_R 0
#define CHOICE_C 1

int side_len, triangle_num, triangle[15],
 data_map[55][55][2]; //0 正 1 倒
int col_num[55][2];
bool isOK, num_map[26];

bool cmp(const int &a, const int &b)
{
	return a<b;
}

int DFS_ROW(int row, int col, int choice)
{
	int i, j, lenth, k, s, last_lenth;
	bool ok ;
	switch (choice)
	{
	case CHOICE_R:
		for (; col <= col_num[row][1]; col++)
		{
			if (data_map[row][col][0])
			{
				break;
			}
		}
		if (col > col_num[row][1])
		{
			return DFS_ROW(row, col_num[row][0], CHOICE_C);
		}
		last_lenth = col;
		for (i = 0; i< triangle_num; i++)
		{
			lenth = triangle[i];
			if (row+lenth > 2*side_len || col+lenth-1 > col_num[row][1])
			{
				return 0;
			}
			for (k = last_lenth; k < col+lenth; k++)
			{
				if (!data_map[row][k][0])  //已被填充
				{
					return 0;	//失败
				}
			}
			last_lenth = k;
			for (j = row; j< row+lenth; j++)
			{
				for (k = col; k < col+lenth-j+row; k++)
				{
					data_map[j][k][0] = 0;
					if (k != col)
					{
						data_map[j][k][1] = 0;
					}
				}
		
			}//寻找下个点
			ok = 1;
			for (j = col+lenth; j<= col_num[row][1]; j++)
			{
				if (data_map[row][j][0])
				{
					if (DFS_ROW(row, j, CHOICE_R))
					{
						return 1;
					}
					else
					{	
						ok = 0;
					}
					break;
				}
			}
			if (j > col_num[row][1])
			{			
				if (!DFS_ROW(row, col_num[row][0], CHOICE_C))
					ok = 0;
				else
					return 1;
			}
			//恢复点
			if (!ok)
			{
				for (s = row; s< row+lenth; s++)
				{
					for (k = col; k < col+lenth-s+row; k++)
					{
						data_map[s][k][0] = 1;
						if (k != col)
						{
							data_map[s][k][1] = 1;
						}
					}
				}
			}
		}
		break;
	case CHOICE_C:
		for (; col <= col_num[row][1]; col++)
		{
			if (data_map[row][col][1])
			{
				break;
			}
		}
		if (col > col_num[row][1])
		{
			if (row == 2*side_len-1)	//搜索完毕	
				return 1;
			else
				return DFS_ROW(row+1, col_num[row][0], CHOICE_R);
		}
		for (i = 0; i< triangle_num; i++)
		{
			lenth = triangle[i];
			if (row+lenth > 2*side_len || col > col_num[row+lenth-1][1] || col-lenth+1 < col_num[row+lenth-1][0])
			{
				return 0;
			}
			for (j = row, k = col; j< row+lenth && k > col-lenth; j++, k--)
			{
				if (!data_map[j][col][1] || !data_map[j][k][1])
				{
					return 0;
				}
			}
			for (j = row; j< row+lenth; j++)
			{
				for (k = col-j+row; k <= col ; k++)
				{
					data_map[j][k][1] = 0;
					if (k != col)
					{
						data_map[j][k][0] = 0;
					}
				}
				
			}//寻找下个点
			ok = 1;
			for (j = col+1; j<= col_num[row][1]; j++)
			{
				if (data_map[row][j][1])
				{
					if (DFS_ROW(row, j, CHOICE_C))
					{
						return 1;
					}
					else
					{	
						ok = 0;
					}
					break;
				}
			}
			if (j > col_num[row][1])
			{		
				if (row == 2*side_len-1)
					return 1;
				if (!DFS_ROW(row+1, col_num[row+1][0], CHOICE_R))
					ok = 0;
				else
					return 1;
			}
			//恢复点
			if (!ok)
			{
				for (j = row; j< row+lenth; j++)
				{
					for (k = col-j+row; k <= col ; k++)
					{
						data_map[j][k][1] = 1;
						if (k != col)
						{
							data_map[j][k][0] = 1;
						}
					}
				}
			}
		}
		break;
	}
	return 0;
}

inline void solve()
{
	memset(data_map, 0, sizeof(data_map));
	int i, j;
	for (i = 0; i<= side_len; i++)
	{
		for (j = side_len - i; j <= side_len*2; j++)
		{
			data_map[i][j][0] = data_map[i][j][1] = 1;
			if (j == side_len*2)
			{
				data_map[i][j][0] = 0;
			}
		}
		col_num[i][0] = side_len - i;
		col_num[i][1] = side_len*2;
	}
	for (i = side_len; i< 2*side_len; i++)
	{
		for (j = 0; j < 3*side_len-i; j++)
		{
			data_map[i][j][0] = data_map[i][j][1] = 1;
			if ( j == 0 )
			{
				data_map[i][j][1] = 0;
			}
		}
		col_num[i][0] = 0;
		col_num[i][1] = 3*side_len-i-1;
	}
	data_map[side_len][2*side_len][1] = 0;
	if (DFS_ROW(0, side_len, CHOICE_R))
	{
		isOK = 1;
	}
}

int main()
{
	int sum, i, j, k, tmp_triangle[15];
	cin>>sum;
	while (sum--)
	{
		cin>>side_len>>triangle_num;
		isOK = 0;
		k = 0;
		memset(num_map, 0, sizeof(num_map));
		for (i = 0; i< triangle_num; i++)
		{
			cin>>tmp_triangle[i];
			if (side_len % tmp_triangle[i] == 0)
			{
				isOK = 1;
				goto my_stop;
			}
			if (tmp_triangle[i] > side_len)
			{
				isOK = 0;
				goto my_stop;
			}
			if (!num_map[tmp_triangle[i]])
			{
				triangle[k++] = tmp_triangle[i];
				for (j = tmp_triangle[i]; j < 26; j += tmp_triangle[i])
				{
					num_map[j] = 1;
				}
			}
		}
		triangle_num = k;
		sort(triangle, triangle+triangle_num, cmp);
		solve();

my_stop:
		if (isOK)
		{
			printf("YES\n");
		}
		else
		{
			printf("NO\n");
		}
	}
    return 0;
}