84.柱状图的最大矩形

84. 柱状图中最大的矩形 - 力扣（LeetCode）

注意首尾加0的细节就可

class Solution {public int largestRectangleArea(int[] heights) {Deque<Integer> stack = new LinkedList<>();int[] newHeight = new int[heights.length + 2];System.arraycopy(heights, 0, newHeight, 1, heights.length);newHeight[heights.length+1] = 0;newHeight[0] = 0;int res = 0;for(int i = 0;i<newHeight.length;i++){while(!stack.isEmpty()&&newHeight[i]<newHeight[stack.peek()]){int right = i;int mid = stack.pop();int left = stack.peek();int h = newHeight[mid];int w = right-left-1;res = Math.max(res,h*w);}stack.push(i);}return res;}
}