[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 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.

최대로 채울 수 있는 물의 양을 구하기

 

Example 1:

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

Explanation: 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 2:

Input: height = [1,1] Output: 1

 

Example 3:

Input: height = [4,3,2,1,4] Output: 16

 

Example 4:

Input: height = [1,2,1] Output: 2

 

Constraints:

• 2 <= height.length <= 3 * 104
• 0 <= height[i] <= 3 * 104

 

풀이:

- 백준의 나무 문제와 유사하게 생겼다. 어렵지 않게 투포인터로 푸는 것으로 예측할 수 있다.

- 두 막대기 중 작은 막대기에 따라 물의 양이 정해지므로 현재 위치에서 더 작은 막대기를 바꾼다.

class Solution {
public:
    int maxArea(vector<int>& height) {
        int start = 0, end = height.size()-1;
        int minLen = 30000 + 1;
        int maxWid = 0;
        
        while(start<end){
            
            minLen = min(height[start], height[end]);
            maxWid = max(maxWid, minLen * (end-start));
            
            if(height[start] < height[end]){
                start++;
            }else{
                end--;
            }
        }
        return maxWid;
    }
};