柱状图中最大的矩形

/*
 * Problem Statement:
 * Given n non-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of the largest rectangle in the histogram.
 * 
 * Approach (Java Stream):
 * Java Stream API is not the most suitable tool for this specific problem because of its imperative nature requiring stack and iterative steps. However, we can illustrate a basic flow using stream for input handling or similar simple operations. This code doesn't leverage Java Stream for the core logic.
 */
 
import java.util.Arrays;
import java.util.Stack;
 
public class Solution {
    public int largestRectangleArea(int[] heights) {
        if (heights == null || heights.length == 0) return 0;
        Stack<Integer> stack = new Stack<>();
        int maxArea = 0;
        int n = heights.length;
 
        for (int i = 0; i <= n; i++) {
            int h = (i == n) ? 0 : heights[i];
            while (!stack.isEmpty() && h < heights[stack.peek()]) {
                int height = heights[stack.pop()];
                int width = stack.isEmpty() ? i : i - stack.peek() - 1;
                maxArea = Math.max(maxArea, height * width);
            }
            stack.push(i);
        }
        return maxArea;
    }
}