leetcode@ [84/85] Largest Rectangle in Histogram & Maximal Rectangle

https://leetcode.com/problems/largest-rectangle-in-histogram/

https://leetcode.com/problems/maximal-rectangle/

 class Solution {
 public:
     int largestRectangleArea2(vector<int> height) {
         if(height.size()==) return ;

         int ret = numeric_limits<int>::min();
         for(int i=;i<height.size();++i) {
             int area = height[i];
             int left = i-, right = i+;
             for(;left>= && height[i]<=height[left];--left)  area += height[i];
             for(;right<height.size() && height[i]<=height[right];++right)  area += height[i];
             ret = max(ret, area);
         }
         return ret;
     }
     int largestRectangleArea(vector<int>& height) {
         //return largestRectangleArea2(height);
         if(height.size()==) return ;

         height.push_back(-);
         stack<int> st;
         int ret = numeric_limits<int>::min(), hId, width, area, start;
         for(int i=;i<height.size();++i) {
             if(st.empty()) {
                 st.push(i);
                 start = st.top();
             }
             if(height[st.top()] < height[i]) st.push(i);
             while(!st.empty() && height[st.top()] > height[i]) {
                     hId = st.top(); st.pop();
                     width = st.empty()? i-start: i-st.top()-;
                     ret = max(ret, width * height[hId]);
             }
             st.push(i);
         }
         return ret;
     }
 };

 class Solution {
 public:
     void clear(vector<int> &vec) {
         for(int i=;i<vec.size();++i) vec[i] = ;
     }
     void clearStack(stack<int> &st) {
         while(!st.empty()) st.pop();
     }
     int largestRectangleArea(vector<int>& height) {
         if(height.size()==) return ;

         height.push_back(-);
         stack<int> st;
         int ret = numeric_limits<int>::min(), hId, width, area, start;
         for(int i=;i<height.size();++i) {
             if(st.empty()) {
                 st.push(i);
                 start = st.top();
             }
             if(height[st.top()] < height[i]) st.push(i);
             while(!st.empty() && height[st.top()] > height[i]) {
                     hId = st.top(); st.pop();
                     width = st.empty()? i-start: i-st.top()-;
                     ret = max(ret, width * height[hId]);
             }
             st.push(i);
         }
         return ret;
     }
     int maximalRectangle(vector<vector<char>>& matrix) {
         if(matrix.size() == ) return ;

         vector<int> height(matrix[].size());

         int ret = numeric_limits<int>::min(), start;
         for(int i=;i<matrix.size();++i) {
             for(int j=;j<matrix[].size();++j) {
                 if(matrix[i][j]=='') height[j]++;
                 else height[j] = ;
             }

             ret = max(ret, largestRectangleArea(height));
         }

         return ret;
     }
 };