当前位置： 移动技术网 > IT编程>脚本编程>Python > 167. Two Sum II - Input array is sorted [medium] (Python)

167. Two Sum II - Input array is sorted [medium] (Python)

2018年04月05日  | 移动技术网IT编程  | 我要评论

苏州经典反串,我们约会吧女嘉宾出场音乐,三晋网

题目链接

https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/

题目原文

Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.

You may assume that each input would have exactly one solution.

Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2

思路方法

注意题目说了两个重要条件：1，有序数组；2，有唯一解。所以解的两个数一定都是数组中唯一存在的数。

思路一

利用两个指针从数组的两侧开始向中间移动，寻找第一对和为target的两个数即为所求。

代码

class Solution(object):
    def twoSum(self, numbers, target):
        """
        :type numbers: List[int]
        :type target: int
        :rtype: List[int]
        """
        left, right = 0, len(numbers) - 1
        while left < right:
            if numbers[left] + numbers[right] == target:
                return [left + 1, right + 1]
            elif numbers[left] + numbers[right] > target:
                right -= 1
            else:
                left += 1

思路二

扫描数组，用字典记录扫描历史，并判断可能成对的另一个数是否在数组中。

代码

class Solution(object):
    def twoSum(self, numbers, target):
        """
        :type numbers: List[int]
        :type target: int
        :rtype: List[int]
        """
        num_dict = {}
        for i, num in enumerate(numbers):
            if (target - num) in num_dict:
                return [num_dict[target - num], i + 1]
            num_dict[num] = i + 1

您可能感兴趣的文章:

如对本文有疑问，请在下面进行留言讨论，广大热心网友会与你互动！！ 点击进行留言回复

相关文章:

验证码：
最近更新的文章
大家感兴趣的文章
移动技术网