[leetcode] 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.

https://oj.leetcode.com/problems/container-with-most-water/

思路1：O(n^2)複雜窮舉全部的狀況，too young too simple.

思路2：:兩個指針i,j分別指向首位，選擇兩者中小的向中間移動，同時更新最大值。這個想法的基礎是，若是i的長度小於j，若是移動j，短板在i，不可能找到比當前記錄的area更大的值了，只能經過移動i來找到新的可能的更大面積。

public class Solution {
    public int maxArea(int[] height) {
        int n = height.length;
        int maxA = 0;
        int curA = 0;
        int i = 0, j = n - 1;
        while (i < j) {
            if (height[i] <= height[j]) {
                curA = Math.abs(j - i) * height[i];
                if (curA > maxA)
                    maxA = curA;
                i++;
            } else {
                curA = Math.abs(j - i) * height[j];
                if (curA > maxA)
                    maxA = curA;
                j--;
            }
        }

        return maxA;
    }

    public static void main(String[] args) {
        System.out.println(new Solution().maxArea(new int[] { 2, 2, 2 }));
        System.out.println(new Solution().maxArea(new int[] { 1, 2, 3 }));
        System.out.println(new Solution().maxArea(new int[] { 2, 3, 3 }));

    }

}

參考：

http://blog.csdn.net/wzy_1988/article/details/17248209

http://www.cnblogs.com/zhaolizhen/p/Containerwater.html