两数之和-python

class Solution:
    # 排序 + 双指针
    def twoSum1(self, nums, target):
        n = len(nums)
        # 升序
        nums.sort()
        # 声明双指针索引
        l = 0
        r = len(nums) - 1
        while (l < r):
            if (nums[l] + nums[r] < target):
                l = l + 1
            elif (nums[l] + nums[r] > target):
                r = r - 1
            else:
                return [l, r]
        return []

    # 空间换时间  先把出现的值进行预存  然后target - nums[i]看是否有预存的值  有的话就符合要求了  取出
    def twoSum2(self, nums, target):
        n = len(nums)
        mapper = {}
        for i in range(n):
            if (target - nums[i] in mapper):
                return [mapper[target - nums[i]], i]
            else:
                mapper[nums[i]] = i
        return []


a = Solution()
print(a.twoSum1([1, 2, 11, 2, 3, 7, 15], 9))