# LeetCode - 0838. Push Dominoes
### 題目網址：https://leetcode.com/problems/push-dominoes/
###### tags: `LeetCode` `Medium` `模擬`

/*
    -LeetCode format-
    Problem: 838. Push Dominoes
    Difficulty: Medium
    
    by Inversionpeter
*/



static const auto Initialize = []{
    ios::sync_with_stdio(false); cin.tie(nullptr);
    return nullptr;
}();

inline void PushdownLeft(string &states, int nowAt) {
    while ((--nowAt) >= 0 && states[nowAt] == '.')
        states[nowAt] = 'L';
}

inline void PushdownRight(string &states, int nowAt) {
    if (nowAt == -1)
        return;
    while ((++nowAt) != states.size() && states[nowAt] == '.')
        states[nowAt] = 'R';
}

inline void PushdownLeftNRight(string &states, int &towardRight, int towardLeft) {
    if (towardRight == -1) {
        PushdownLeft(states, towardLeft);
        return;
    }
    while ((++towardRight) < (--towardLeft)) {
        states[towardRight] = 'R';
        states[towardLeft] = 'L';
    }
    towardRight = -1;
}

class Solution {
public:
    string pushDominoes(string dominoes) {
        int rightMostR = -1;
        for (int i = 0; i != dominoes.size(); ++i)
            switch (dominoes[i]) {
                case 'L':
                    PushdownLeftNRight(dominoes, rightMostR, i);
                    break;
                case 'R':
                    PushdownRight(dominoes, rightMostR);
                    rightMostR = i;
                    break;
            }
        PushdownRight(dominoes, rightMostR);
        return dominoes;
    }
};