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class Solution {
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 public:
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  string pushDominoes(string dominoes) {
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#define SET(ch, arr)             \
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  if (dominoes[i] == ch) {       \
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    count = 1;                   \
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    prev = ch;                   \
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  } else if (dominoes[i] != '.') \
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    prev = dominoes[i];          \
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  if (prev == ch && dominoes[i] == '.') arr[i] = count++;
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    string res = "";
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    char prev;
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    int n = dominoes.size(), count = 1;
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    vector<int> left(n, 0), right(n, 0);
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    for (int i = 0; i < n; i++) {
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      SET('R', right);
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    }
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    prev = '.';
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    for (int i = n - 1; i >= 0; i--) {
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      SET('L', left);
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    }
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    for (int i = 0; i < n; i++) {
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      if (!left[i] && !right[i])
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        res += dominoes[i];
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      else if (!left[i])
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        res += 'R';
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      else if (!right[i])
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        res += 'L';
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      else if (left[i] == right[i])
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        res += '.';
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      else if (left[i] < right[i])
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        res += 'L';
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      else
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        res += 'R';
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    }
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    return res;
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  }
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};