题解： - 力扣（LeetCode）

class Solution {public int largestRectangleArea(int[] heights) {Stack<Integer> stack = new Stack<>();int maxArea = Integer.MIN_VALUE;for(int i = 0;i < heights.length;i++){int curHeight = heights[i];while(!stack.empty() && curHeight < heights[stack.peek()]){int index = stack.pop();int left = (stack.empty()) ? 0 : stack.peek()+1;int tempArea = heights[index] * (i - left);maxArea = Math.max(maxArea,tempArea);}stack.push(i);     }while(!stack.empty()){int index = stack.pop();int left = (stack.empty()) ? 0 : stack.peek()+1;int tempArea = heights[index] * (heights.length - left);maxArea = Math.max(maxArea,tempArea);}return maxArea;}
}