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class Solution {
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 public:
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  vector<int> replaceElements(vector<int> &arr) {
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    int n = arr.size();
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    // taking last index as greatest for now
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    int g = arr[n - 1];
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    // setting last index as -1
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    arr[n - 1] = -1;
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    for (int i = n - 2; i >= 0; i--) {
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      // storing last index value to be changed to comapare with the greatest
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      // value till now
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      int h = arr[i];
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      // assigning greatest till now from right
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      arr[i] = g;
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      // checking if current is greater than the previous indices
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      if (h > g) {
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        g = h;
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      }
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    }
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    // returning the value
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    return arr;
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  }
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};