【LeetCode】42. 接雨水

class Solution {
public:
    int trap(vector<int>& height) {
        int n = height.size();
        vector<int> left(n), right(n);
        for(int i =1; i < n; i++){
            left[i] = max(left[i-1], height[i-1]);
        }for(int i =n-2; i>=0;i--){
            right[i]= max(right[i + 1], height[i+1]);
        }int water= 0;
        for(int i=0;i<n;i++){
            int level = min(left[i],right[i]);
            water += max(0, level-height[i]);
        }return water;
    }
};