Leetcode 11 Container With Most Water

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

這個題意為求容器中可以裝的水，可以使用暴力法或者是雙指標法

1）暴力

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

2）雙指標

class Solution {
    public int maxArea(int[] height) {
         int length = height.length;
	   int maxAres = (length-1)*Math.min(height[0],height[length-1]);
	   int temp = 0;
	   int left = 0;
	   int right = length-1;
	   while(left<right){
		   int temMax = (right-left)*Math.min(height[right],height[left]);
		   if(temMax>maxAres) maxAres = temMax;
		   if(height[left]<height[right]){
			   temp = left;
			   while(height[temp]>=height[left]&&left<right){
				   left++;
			   }
		   }
		   else{
			   temp = right;
			   while(height[temp]>=height[right]&&left<right){
				   right--;
			   }
		   }
	   }
        
	   return maxAres;
    }
}

單詞：slant  axis