Maximum Width Ramp LeetCode solution in C++

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class Solution {
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 public:
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  int maxWidthRamp(vector<int> &nums) {
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    int n = nums.size();
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    if (n == 2) {
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      if (nums[0] <= nums[1]) return 1;
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      return 0;
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    }
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    stack<int> st;
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    for (int i = 0; i < n; i++) {
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      if (st.empty() || nums[i] < nums[st.top()]) {
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        st.push(i);
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      } // maintaining a monotonic decreasing stack
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    }
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    int ramp = 0;
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    for (int i = n - 1; i >= 0; i--) {
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      while (!st.empty() && nums[i] >= nums[st.top()]) {
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        ramp = max(ramp, i - st.top());
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        st.pop();
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      }
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    }
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    return ramp;
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  }
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};