代码随想录算法训练营 Day 60 | 84.柱状图中最大的矩形

84.柱状图中最大的矩形

讲解链接：代码随想录-84.柱状图中最大的矩形

注意数组扩容。

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