1. Two Sum
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.
Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9, return [0, 1].
给定一个数组,里面存放着一组整数,然后给定一个目标整数,求在数组中的相加和为目标数的两个数的索引。
这个题目其实比较简单,类似于一群人相互握手,握手的次数为:n * (n-1) / 2, 我们只要进行两层循环,尝试所有相加和组合即可。