[leetcode]84 largest Rectangle in histogram

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

http://blog.csdn.net/linhuanmars/article/details/20524507

Public class solution {    public int largestrectanglearea (int[]  height)      {        // solution  a        // return largestrectanglearea_expand (height) ;                //  Solution b        return largestrectanglearea_stack (height);     }        ////////////////////     // Solution A: Stack    //    private  Int largestrectanglearea_stack (int[] h)     {         if  (h == null | |  h.length == 0)             return 0;   // invalid input                     Stack<Integer>  stack = new Stack<Integer> (        int);  max = 0;        for  (int i = 0  ; i < h.length ; i ++)         {             while  (!stack.empty ()  & & h[i] <= h[stack.peek ()])              {                 Int last = stack.pop ();                 int area = 0;                 if  (Stack.empty ())                  {                     area = i * h[last];                 }                 else                 {                     //  next   stack.peek ()  + from the top element of the current stack  1 to                      //  current subscript  i  (exclusive)                      //  is larger than the stack element height                      area =  (i -  ( Stack.peek ()  + 1)  * h[last];                 }                 max = math.max (Max, area);             }                         stack.push (i);         }                 while  (!stack.empTy ())         {             int last = stack.pop ();             int area = 0;             if  (Stack.empty ())             {                 area =  h.length * h[last];            }             else             {                 area =  (H.length - stack.peek ()  - 1)  * h [LAST];&NBSP;&NBSP;&NBSP;&NBsp;        }             max = math.max (Max, area);         }                 return  max;    }        ////////////////////     // Solution B: Expand    //    //  For each bar i,  search   leftmost  >= h[i]   index    //  same   Find the right      //  calculate the maximum     //     //  o (n ^ 2)     private int largestrectanglearea_expand (int[] h )     {        int max = 0;         for  (int i = 0 ; i < h.length ; i ++)         {             // find left            int  l = i;            while  (l  >= 0 && h[l] >= h[i])                  l --;             l++;                         // find right             int r = i;             while  (R < h.length && h[r] >= h[i])                  r ++;             r --;                          max = math.max (max, h[i] *  (r - l + 1));         }        return max;     }}

[leetcode]84 largest Rectangle in histogram