LeetCode 11. 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.

稍微优化的暴力搜索，时间复杂度比O(n^2)稍低。

C:

int maxArea(int height[], int n) {
    int max = 0, len = n;
    for(int i = 0; i < len; i++){
        if(height[i] * (len - i - 1) <= max)continue;
        for(int j = i + (max / height[i] > 1 ? max / height[i] : 1); j < len; j++){
            int area = (j - i) * (height[i] < height[j] ? height[i] : height[j]);
            if(area > max)max = area;
        }
    }
    
    return max;
}

使用双指针的方法，从数组两端向中间遍历，时间复杂度约为O(n)。

C++:

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