0011. Container With Most Water

Medium | Two Pointer | 648 ms (94.80%), 27.1 MB (88.44%)

❓ Problem Statement

Source: LeetCode - Container With Most Water GitHub: Solution / Performance

Given n non-negative integers a1, a2, ..., an , where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of the line i is at (i, ai) and (i, 0). Find two lines, which, together with the x-axis forms a container, such that the container contains the most water.

Notice that you may not slant the container.

✍🏻 Constraints & Example

💡 Ideas

To begin with the potential maximum, we use two pointers from left- and right-most elements (due to the LARGEST gap in between).

Calculate the size of the container in each iteration, and move the pointer with SHORTER height until l >= r.

🤖 Python3

class Solution:
    def maxArea(self, height: List[int]) -> int:
        # (base case)
        if len( height ) == 2: return min( height )
        
        # ==================================================
        #  Array + Two Pointer                             =
        # ==================================================
        # time  : O(n)
        # space : O(1)
        
        area = 0
        l, r = 0, len(height) - 1
        
        # start from both-side (due to the LARGEST gap)
        # move the pointer with SHORTER height
        while r > l:
            tmp = min(height[l], height[r]) * (r - l)
            if tmp > area: area = tmp
            
            if height[r] > height[l]: l += 1
            else: r -= 1
                
        return area

🤖 Java