11.Container-With-Most-Water

11. Container With Most Water

题目地址

https://leetcode.com/problems/container-with-most-water/

题目描述

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.

Example:

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

代码

Approach 1: Brute Force

class Solution {
  public int maxArea(int[] height) {
    int maxarea = 0;
    for (int i = 0; i < height.length; i++) {
      for (int j = i + 1; j < height.length; j++) {
        maxarea = Math.max(maxarea, Math.min(height[i], height[j]) * (j - i));
      }
    }
  }
}

Approach #2 Two Pointer Approach

Complexity Analysis

• Time complexity : O_(_n). Single pass.

• Space complexity : O(1). Constant space is used.

class Solution {
  public int maxArea(int[] height) {
    int maxarea = 0, l = 0, r = height.length - 1;
    while (l < r) {
      maxarea = Math.max(maxarea, Math.min(height[l], height[r]) * (r - l));
      if (height[l] < height[r]) {
        l++;
      } else {
        r--;
      }
    }
    return maxarea;
  }
}