【LeetCode】 141 接雨水

題目：


解題思路：

雙指針法，具體的要看視頻講解

https://leetcode-cn.com/problems/trapping-rain-water/solution/jie-yu-shui-by-leetcode/

代碼：

public class LC108 {
    public int trap(int[] height) {
        int left = 0, right = height.length - 1;
        int ans = 0;
        int left_max = 0, right_max = 0;
        while (left < right) {
            if (height[left] < height[right]) {
                if (height[left] >= left_max) {
                    left_max = height[left];
                } else {
                    ans += (left_max - height[left]);
                }
                ++left;
            } else {
                if (height[right] >= right_max) {
                    right_max = height[right];
                } else {
                    ans += (right_max - height[right]);
                }
                --right;
            }
        }
        return ans;
    }


}