LeetCode 723. 粉碎糖果（模拟）

样例 :
输入:
board = 
[[110,5,112,113,114],
[210,211,5,213,214],
[310,311,3,313,314],
[410,411,412,5,414],
[5,1,512,3,3],
[610,4,1,613,614],
[710,1,2,713,714],
[810,1,2,1,1],
[1,1,2,2,2],
[4,1,4,4,1014]]
输出:
[[0,0,0,0,0],[0,0,0,0,0],[0,0,0,0,0],
[110,0,0,0,114],[210,0,0,0,214],
[310,0,0,113,314],[410,0,0,213,414],
[610,211,112,313,614],[710,311,412,613,714],
[810,411,512,713,1014]]

注释 :
board 数组的行数区间是 [3, 50]。
board[i] 数组的长度区间（即 board 数组的列数区间）是 [3, 50]。
每个 board[i][j] 初始整数范围是 [1, 2000]。

class Solution {
public:
    vector<vector<int>> candyCrush(vector<vector<int>>& b) {
    	bool todo = false;
    	int m = b.size(), n = b[0].size(), i, j, up, down;
    	for(i = 0; i < m; ++i)//横向检查
    		for(j = 0; j < n-2; ++j)
    		{
                if(b[i][j] == 0)
                    continue;
    			if(abs(b[i][j])==abs(b[i][j+1]) && abs(b[i][j+1])==abs(b[i][j+2]))
    			{
    				b[i][j] = b[i][j+1] = b[i][j+2] = -abs(b[i][j]);//标记为负的
    				todo = true;
    			}
    		}
    	for(j = 0; j < n; ++j)//纵向检查
    		for(i = 0; i < m-2; ++i)
    		{
                if(b[i][j] == 0)
                    continue;
    			if(abs(b[i][j])==abs(b[i+1][j]) && abs(b[i+1][j])==abs(b[i+2][j]))
    			{
    				b[i][j] = b[i+1][j] = b[i+2][j] = -abs(b[i][j]);//标记为负的
    				todo = true;
    			}
    		}
    	for(i = 0; i < m; ++i)//负的 标记为0要删除
    		for(j = 0; j < n; ++j)
    			if(b[i][j] < 0)
    				b[i][j] = 0;
    	for(j = 0; j < n; ++j)//纵向掉落
    	{
    		down = up = m-1;//从最底下开始往上找
    		while(down >= 0)
    		{	//双指针搬移数据
    			if(b[down][j] == 0)//底下待填
    			{
                    up = min(down, up);//up记住上次的位置
    				while(up >= 0 && b[up][j] == 0)
    					up--;
    				if(up >= 0)//上面找到糖果
    					swap(b[down][j], b[up][j]);//交换
                    else
                        break;//找完了
    			}
    			down--;
    		}
    	}
    	if(todo)
    		candyCrush(b);
    	return b;
    }
};