[leetcode] 838. Push Dominoes : https://leetcode.com/problems/push-dominoes/description/

Push Dominoes.cc

class Solution {
public:

    string pushDominoes(string dominoes) {
        int len = dominoes.size();
        vector<int> cnt(len, 0);
        for (int i = 0; i < len; i++) {
            char now = dominoes[i];
            if (now == '.') continue;
            if (now == 'L') {//-1
                cnt[i] = -1;
                for (int j = 1; i-j >= 0; j++) {
                    if (dominoes[i - j] != '.') break;
                    if (cnt[i - j] == j) { //1.
                        cnt[i - j] = 0;
                        break;
                    }
                    else if (cnt[i-j] !=0 && cnt[i - j] < j) { //2.
                        break;
                    }
                    cnt[i - j] = -j;
                }
            }
            else { //'R' +1
                cnt[i] = 1;
                for (int j = 1; i + j < len; j++) {
                    if (dominoes[i + j] != '.' ) break;
                    if (cnt[i + j] == -j) { //1.
                        cnt[i - j] = 0;
                        break;
                    }
                    else if (cnt[i + j] != 0 && -cnt[i + j] < j) { //2.
                        break;
                    }
                    cnt[i + j] = j;
                }
            }
        }

        string ans = "";
        for (int i = 0; i < len; i++) {
            if (cnt[i] > 0) ans.push_back('R');
            else if (cnt[i] < 0) ans.push_back('L');
            else ans.push_back('.');
        }
        return ans;
    }

};