LeetCode 11 ·
Medium
Container With Most Water
Pick two lines that, with the x-axis, hold the most water.
Try it
Step through the core mechanic. The simulator below runs the two pointers shape this problem is built on.
Interactive · Two-pointers walkthrough Two Sum II (sorted): find a pair that sums to target.
0
1
L
1
2
2
3
3
5
4
8
5
11
6
14
7
17
8
21
R
start: a[L] + a[R] = 22
Why two pointers works.
Because the array is sorted, every position pair (L, R) is uniquely
determined by its sum's relation to the target. If
sum < target,
moving L right is the only way to grow the sum without moving R; if sum > target,
moving R left is the only way to shrink it. The pointers never need to revisit —
that's why it's O(n) instead of the obvious O(n²).The approach
Pointers at both ends; area is width × min(height). Always move the shorter wall inward — moving the taller one can only shrink the area, so the shorter side is the only move that can help.
| Aspect | Value |
|---|---|
| Pattern | Two pointers |
| Recognise it by | Max area between two lines. |
| Time complexity | O(n) |
| Space complexity | O(1) |
| Difficulty | Medium |
Who asks it
Companies known to ask this problem, from public LeetCode company-tag aggregations. A signal of where to expect it, not a guarantee.