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.

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Implement atoi to convert a string to an integer.

Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.

Notes: It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.

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Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

Solution:

class Solution:
    def reverse(self, x):
        answer = 0
        sign = 1 if x > 0 else -1
        x = abs(x)
        while x > 0:
            answer = answer * 10 + x % 10
            x /= 10
        return sign*answer