Find the Student that Will Replace the Chalk LeetCode solution in C++

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class Solution {
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 public:
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  // T(n) = O(n) S(n) = O(1)
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  int chalkReplacer(vector<int> &chalk, int k) {
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    // Size of the vector
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    int n = chalk.size();
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    // Store the sum of the elements in the vector
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    long sum = 0;
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    // Calculate the sum of the elements
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    for (int n : chalk) sum += n;
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    // Update k as the remainder of the sum
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    // to make sure that the while loop
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    // will traverse the vector at most 1 time
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    k = k % sum;
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    // Start from the initial value in the array
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    int idx = 0;
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    // While the next student has enough chalk
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    while (k >= chalk[idx]) {
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      // Decrease the remaining chalk
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      k -= chalk[idx];
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      // Increase the index
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      idx = (idx + 1) % n;
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    }
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    // Return the index of the student without
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    // enough chalk
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    return idx;
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  }
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};