题解 | #接雨水问题#

using System;
using System.Collections.Generic;


class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * max water
     * @param arr int整型一维数组 the array
     * @return long长整型
     */
    public long maxWater (List<int> arr) {
        int left = 0, right = arr.Count - 1;
        long res = 0;
        int i = -1;
        while(left < right){
            if(arr[left] <= arr[right]){
                for(i = left + 1; i < right; i++){
                    if(arr[i] > arr[left]){
                        left = i;
                        break;
                    }
                    res += arr[left] - arr[i];
                    //Console.WriteLine("left++"+res);
                }
                if(i == right) break;
            }
            else{
                for(i = right - 1; i > left; i--){
                    if(arr[i] > arr[right]){
                        right = i;
                        break;
                    }
                    res += arr[right] - arr[i];
                    //Console.WriteLine("right--"+res);
                }
                if(i == left) break;
            }
        }
        return res;
    }
}