Container With Most Water

There are n vertical lines; line i stands at position i with height h[i]. Choose two lines that, together with the x-axis, hold the most water. The water held by lines i < j is (j − i) × min(h[i], h[j]).

Input:

• line 1: n
• line 2: n heights

Output: the maximum amount of water.

Constraints: 2 ≤ n ≤ 10⁵, 0 ≤ h[i] ≤ 10⁴.

Think about it: start with the widest container (both ends). Moving the taller line inward can never help — so always move the shorter one.