Cacher is the code snippet organizer for pro developers

class Solution {
public:
    int trap(vector<int>& height) {
        int n = height.size();
        int left = 0, right = n - 1;
        int lmax = 0, rmax = 0;
        int res = 0;
        while (left < right) {
            if (height[left] < height[right]) {
                lmax = max(lmax, height[left]);
                res += lmax - height[left++];
            }
            else {
                rmax = max(rmax, height[right]);
                res += rmax - height[right--];
            }
        }
        return res;
    }
};