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Candy Crush

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Description

https://leetcode.com/problems/candy-crush/

Solution

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class Solution {
public:
    vector<vector<int>> candyCrush(vector<vector<int>>& board) {
        int m = board.size();
        int n = board[0].size();
        
        while(true) {
            vector<pair<int, int>> del;
            for (int i = 0; i < m; ++i) {
                for (int j = 0; j < n; ++j) {
                    if (board[i][j] == 0) continue;
                    int upper = i + 1, lower = i -1; 
                    int lefter = j - 1, righter = j + 1;
                    while(upper < m && upper - i < 3 
                      && board[upper][j] == board[i][j]) ++upper;
                    while(lower >= 0 && i - lower < 3
                      && board[lower][j] == board[i][j]) --lower;
                    while(righter < n && righter - j < 3
                      && board[i][righter] == board[i][j]) ++righter;
                    while(lefter >= 0 && j - lefter < 3
                      && board[i][lefter] == board[i][j]) --lefter;

                    if (righter -lefter > 3 || upper - lower > 3)
                        del.push_back(make_pair(i, j));
                }
            }
            if (del.size() == 0) break;
            
            for (auto& item:del) board[item.first][item.second] = 0;
            
            //Begin erasing....
            for (int j = 0; j < n; ++j) {
                vector<int> temp;
                for (int i = m - 1; i >= 0; --i) 
                    if(board[i][j] != 0)
                        temp.push_back(board[i][j]);
                
                int k = m - 1;
                int index = 0;
                while(index < temp.size()) {
                    board[k--][j] = temp[index++];
                }
                while(k >= 0) board[k--][j] = 0;
            }
        }
        return board;
    }
};