Leetcode 11. Container With Most Water

Given n non-negative integers a₁, a₂, ..., a_n, where each represents a point at coordinate (i, a_i). n vertical lines are drawn such that the two endpoints of line i is at (i, a_i) 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.

 

1,暴力解

过了所有用例但时间太长

int maxArea(int* height, int heightSize) {
    int max = 0;
    int temp;
    for(int i = 0;i < heightSize;i++)
    {
        for(int j = i + 1;j <heightSize;j++)
        {
            temp = height[i] > height[j]? height[j]:height[i];
            temp *= (j - i);
            if((height[i] == 0) || (height[j] == 0))
                temp = 0;
            max = max > temp?max:temp;
        }
    }
    return max;
}

 2,提交解

减少运行时间的方法在于减少计算次数，发现题目规律为选取较短的一条边和底的乘积是目标值，这样我们可以通过判断较短边来减少循环次数。

class Solution {
public:
    int maxArea(vector<int>& height) {
        int length = height.size();
        int i = 0;
        int j = length - 1;
        int max = 0;
        int temp;
        while(i != j)
        {
            if(height[i] <= height[j])
            {
                temp = height[i] * (j - i);
                i++;
            }else
            {
                temp = height[j] * (j - i);
                j--;
            }
            max = max>temp?max:temp;
        }
        return max;
    }
};