Leetcode/leetcode84.cpp at main · ksaini-web/Leetcode · GitHub

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class Solution {
public:
    int largestRectangleArea(vector<int>& heights) {

        int  n =  heights.size();

         vector<int> right(n,0);
         vector<int> left(n,0);

         stack<int> s;

         for(int i=n-1 ; i>=0 ; i--){

            while(s.size() > 0 && heights[s.top()] >= heights[i]){

                s.pop();
            }

            right[i] =  s.empty() ? n : s.top();

            s.push(i);
         }

          while(!s.empty()){
            s.pop();
          }
          for(int i=0 ; i<n ; i++ ){

            while(s.size()>0 && heights[s.top()]>= heights[i]){
                s.pop();
            }

            left[i] =  s.empty() ? -1 : s.top();

            s.push(i);
         }

         int ans =0 ;

         for(int i = 0 ; i<n; i++ ){

            int width = right[i] - left[i]-1;

            int currarea = heights[i] * width;

            ans = max(currarea , ans);


         }

         return ans;


    }

};