试题:
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:
Input: [1,8,6,2,5,4,8,3,7]
Output: 49
代码:
最简单的是暴力破解,也就是求两个柱子间的面积。
class Solution {
public int maxArea(int[] height) {
int max_area = 0;
for(int i=0; i<height.length; i++){
for(int j=i+1; j<height.length; j++){
max_area = Math.max(max_area, Math.min(height[j],height[i])*(j-i));
}
}
return max_area;
}
}
极端情况下最大的情况是正好处于数组的两端的点。所以我们从数组两端出发,如果不是最大的话,那么显然这两条线中较短的线要被剔除,因为它限制了包含的区域面积。
class Solution {
public int maxArea(int[] height) {
int max_area=0, l=0, r=height.length-1;
while(l<r){
max_area = Math.max(max_area, Math.min(height[r],height[l])*(r-l));
if(height[l] < height[r]){
l++;
}else{
r--;
}
}
return max_area;
}
}