Minimum Domino Rotations For Equal Row LeetCode solution in C++

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class Solution {
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 public:
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  int minDominoRotations(vector<int> &tops, vector<int> &bottoms) {
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    vector<int> freq(7, 0);
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    int n = tops.size();
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    int tile = -1
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               // there has to be particular tile number which is present in
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               // every column to be able to arrange same tile in top or bottom
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               // by rotating check which tile is present in every column
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               for (int i = 0; i < n; ++i) {
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      int top = tops[i];
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      int bottom = bottoms[i];
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      freq[top]++;
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      if (top != bottom) {
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        freq[bottom]++;
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      }
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      //  check for potential tile number
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      if (freq[top] == n) {
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        tile = top;
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      }
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      if (freq[bottom] == n) {
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        tile = bottom;
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      }
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    }
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    if (tile == -1) { // rearrangement not possible
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      return -1;
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    }
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    int tilesTop = 0;
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    int tilesBottom = 0;
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    for (int i = 0; i < n; ++i) {
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      if (tops[i] == bottoms[i]) continue;
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      if (tops[i] == tile) {
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        tilesTop++;
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      }
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      if (bottoms[i] == tile) {
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        tilesBottom++;
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      }
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    }
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    return tilesTop < tilesBottom ? tilesTop : tilesBottom;
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  }
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};