N-Queens II LeetCode solution in C++

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class Solution {
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 public:
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  int totalNQueens(int n) {
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    vector<bool> col(n), diag(2 * n - 1), anti_diag(2 * n - 1);
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    return solve(col, diag, anti_diag, 0);
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  }
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  int solve(vector<bool> &col, vector<bool> &diag, vector<bool> &anti_diag, int row) {
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    int n = size(col), count = 0;
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    if (row == n) return 1;
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    for (int column = 0; column < n; column++)
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      if (!col[column] && !diag[row + column] && !anti_diag[row - column + n - 1]) {
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        col[column] = diag[row + column] = anti_diag[row - column + n - 1] = true;
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        count += solve(col, diag, anti_diag, row + 1);
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        col[column] = diag[row + column] = anti_diag[row - column + n - 1] = false;
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      }
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    return count;
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  }
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};