leetcode 41. 接雨水 [java][双指针]

a​​​​​​​​​​​​​t​​​​​​​t​​​​​​​leetcode 41. 接雨水

    public static
            //leetcode submit region begin(Prohibit modification and deletion)
            
    class Solution {
        public int trap(int[] height) {
            if (height.length < 3) {
                return 0;
            }
            int len = height.length;
            int left = 0, right = len - 1; // 左右双指针
            int leftMax = 0, rightMax = 0; // 左右两边最高的柱子
            // 水的体积 = sumTotal - sumHeight
            int sumTotal = 0; // 柱子+水的体积
            int sumHeight = 0; // 柱子体积
            while (left <= right) {
                int leftHeight = height[left]; // 左边柱子高度
                int rightHeight = height[right]; // 右边柱子高度
//                处理较矮的柱子
                if (leftHeight <= rightHeight) {
//                    左边柱子矮
                    leftMax = Math.max(leftMax, leftHeight); // 左边已遍历过的最高的柱子
                    sumTotal += leftMax; // 增加总的体积
                    sumHeight += leftHeight; // 增加柱子的体积
                    left++;
                } else {
//                    右边柱子矮
                    rightMax = Math.max(rightMax, rightHeight); // 右边已遍历过的最高的柱子
                    sumTotal += rightMax; // 增加总的体积
                    sumHeight += rightHeight; // 增加柱子的体积
                    right--;
                }
            }
            return sumTotal - sumHeight; // 总体积 - 柱子体积
        }
    }
//leetcode submit region end(Prohibit modification and deletion)