11. Container With Most Water

Problem

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 line i is at (i, ai) and (i, 0). Find two lines, which together with x-axis forms a container, such that the container contains the most water.

Note: You may not slant the container and n is at least 2.

The above vertical lines are represented by array [1,8,6,2,5,4,8,3,7]. In this case, the max area of water (blue section) the container can contain is 49.

Example 1:

Input: [1,8,6,2,5,4,8,3,7]
Output: 49

Problem Summary

Given an array of non-negative integers a1, a2, a3, …… an, each integer represents a wall of height ai standing at position x on the coordinate axis. Choose two walls that, together with the x-axis, form a container that can hold the most water.

Solution Approach

This problem also uses the two-pointer approach. Place 2 pointers at the beginning and end respectively, and after each move, determine whether the product of length and width is the maximum.

Code

package leetcode

func maxArea(height []int) int {
	max, start, end := 0, 0, len(height)-1
	for start < end {
		width := end - start
		high := 0
		if height[start] < height[end] {
			high = height[start]
			start++
		} else {
			high = height[end]
			end--
		}

		temp := width * high
		if temp > max {
			max = temp
		}
	}
	return max
}