leetcode第一题(easy)

Posted 2021-02-01 大数据开发程序猿

第一题：题目内容

Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice.
Example: Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9, return [0, 1].

给定一个整数数组和一个目标值，找出数组中和为目标值的两个数。 你可以假设每个输入只对应一种答案，且同样的元素不能被重复利用。
示例: 给定 nums = [2, 7, 11, 15], target = 9
因为 nums[0] + nums[1] = 2 + 7 = 9 所以返回 [0, 1]

今天做了leetcode的第一道题，题意很简单，就是给定一组数和一个目标值，从这组数中找到两个数加起来等于目标值，输出目标值的下标。

刚刚见到这道题，没过脑，直接使用暴力遍历，两个循环嵌套，逐个进行相加运算，复杂度是O(n^2)

def twoSum( nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        l=list()
        for i in range(len(nums)):
            print(‘i=‘,i)
            for j in range(i+1,len(nums)):
                print(‘j=‘,j)
                if nums[i]+nums[j]==target:
                    l.append(i)
                    l.append(j)
        return l

　查找了别人写的之后感觉还是大神厉害的哈哈，自己提交之后AC了

def twoSum( nums, target):
    sum=[]
    for i in range(len(nums)):
        one = nums[i]
        second = target-nums[i]
        if second in nums:
            j = nums.index(second)
            if i!=j:
                sum.append(i)
                sum.append(j)
    return sum