leetcode—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.

class Solution {
    public int maxArea(int[] height) {
        if(height==null || height.length<=0) return 0;
        int index1 = 0;
        int index2 = height.length-1;
        int max = 0;
        while(index1<index2){
            max = Math.max(max,Math.min(height[index1],height[index2])*(index2-index1));
            if(height[index1]<height[index2]){
                index1++;
            }else{
                index2--;
            }
        }
        return max;
    }
}

和Two sum類似，利用夾逼準則，起始條件是一個索引在數組最左邊，另外一個索引在數組最右邊，從兩邊向中間靠攏，前進的準則是兩個索引對應的數組值，如果左邊的比較小，那麼左邊的像右滑動，如果右邊的比較小，右邊的像左滑動，因爲這個裝水是利用的短板原理，如果左邊的比較小，滑動他，有可能會變大，但是滑動右邊的，一定會變小，因爲不是橫座標變小了就是縱座標變小