> For the complete documentation index, see [llms.txt](https://abhyas-kanaujia.gitbook.io/interviewbit-amazon/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://abhyas-kanaujia.gitbook.io/interviewbit-amazon/08-stacks-and-queues/rain-water-trapping.md).

# Rain Water Trapping

{% embed url="<https://www.interviewbit.com/problems/rain-water-trapped/>" %}

```cpp
int Solution::trap(const vector<int> &A) {
    deque<int> maxLeft = {A.front()};
    deque<int> maxRight = {A.back()};
    
    for(int i = 1; i < A.size(); i++) 
        maxLeft.push_back(max(maxLeft.back(), A[i]));
    
    for(int i = A.size() - 2; i >= 0; i--) 
        maxRight.push_front(max(maxRight.front(), A [i]));
        
    int totalWaterTrapped = 0;
    
    for(int i = 1; i < A.size() - 1; i++) 
        totalWaterTrapped += min(maxLeft[i], maxRight[i]) - A[i];
        
    return totalWaterTrapped;    
}
```