Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining. Example: Input: height = [0,1,0,2,1,0,1,3,2,1,2,1] Output: 6 Explanation: Water is trapped in the basins formed between taller bars. Pattern focus: Monotonic Decreasing Stack for bounded valleys.
height = elevation map
total trapped water units
Example 1:
Input:
height = [0,1,0,2,1,0,1,3,2,1,2,1]
Output:
6
Explanation:
Each bounded basin contributes water based on the lower of the two walls.
Example 2:
Input:
height = [4,2,0,3,2,5]
Output:
9
Explanation:
Multiple basins can be accumulated independently.