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()==0) return 0;
        
        int ret = numeric_limits<int>::min();
        for(int i=0;i<height.size();++i) {
            int area = height[i];
            int left = i-1, right = i+1;
            for(;left>=0 && 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()==0) return 0;
        
        height.push_back(-1);
        stack<int> st;
        int ret = numeric_limits<int>::min(), hId, width, area, start;
        for(int i=0;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()-1;
                    ret = max(ret, width * height[hId]);
            }
            st.push(i);
        }
        return ret;
    }
};

class Solution {
public:
    void clear(vector<int> &vec) {
        for(int i=0;i<vec.size();++i) vec[i] = 0;
    }
    void clearStack(stack<int> &st) {
        while(!st.empty()) st.pop();
    }
    int largestRectangleArea(vector<int>& height) {
        if(height.size()==0) return 0;
        
        height.push_back(-1);
        stack<int> st;
        int ret = numeric_limits<int>::min(), hId, width, area, start;
        for(int i=0;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()-1;
                    ret = max(ret, width * height[hId]);
            }
            st.push(i);
        }
        return ret;
    }
    int maximalRectangle(vector<vector<char>>& matrix) {
        if(matrix.size() == 0) return 0;
        
        vector<int> height(matrix[0].size());
        
        int ret = numeric_limits<int>::min(), start;
        for(int i=0;i<matrix.size();++i) {
            for(int j=0;j<matrix[0].size();++j) {
                if(matrix[i][j]=='1') height[j]++;
                else height[j] = 0;
            }
            
            ret = max(ret, largestRectangleArea(height));
        }
        
        return ret;
    }
};