// 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. // Solution: Start with walls at either end. If the current area is greater than the max area, update it. // At each step, move the shorter wall one step towards the longer wall and recalculate. O(n) complexity. class Solution { public int maxArea(int[] height) { List list = new ArrayList(); int start = 0, end = height.length - 1, multiplier = height.length - 1; int maxarea = Integer.MIN_VALUE; while (multiplier != 0) { maxarea = Integer.max(maxarea, Integer.min(height[start], height[end]) * multiplier--); if (height[start] > height[end]) { end--; } else { start++; } } return maxarea; } }