Trapping rainwater (stack problem) solved with Gemini Pro 2.5

 LINK TO CHAT:
https://g.co/gemini/share/320262b94bda

import java.util.Stack;

class Main {

    public static int trappingRainStack(int[] height) {

        if (height == null || height.length == 0) {

            return 0;

        }

        Stack<Integer> stack = new Stack<>();

        int ans = 0;

        int n = height.length;

        // Main loop to iterate through each bar

        for (int i = 0; i < n; i++) {

            

            // 1. Finding a container: This loop runs when the current bar is a "right wall"

            while (!stack.isEmpty() && height[stack.peek()] < height[i]) {

                // 2. Identifying parts of the container

                // i. The popped bar is the bottom of the container.

                int topIndex = stack.pop();

                int pop_height = height[topIndex];

                // If stack is empty, there is no left wall, so break.

                if (stack.isEmpty()) {

                    break;

                }

                

                // iii. The new top of the stack is the left wall.

                int left_wall_index = stack.peek();

                // ii. The current bar 'i' is the right wall.

                // 3. Calculating the Trapped Water 💧

                int width = i - left_wall_index - 1;

                int min_height = Math.min(height[left_wall_index], height[i]) - pop_height;

                ans += width * min_height;

            }

            

            // Push the current bar's index. It might be a future left wall.

            stack.push(i);

        }

        return ans;

    }

    public static void main(String[] args) {

        int[] arr = {0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1};

        int result = trappingRainStack(arr);

        System.out.println("The total trapped water is: " + result); // Output: 6

    }

}