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].解法：
class Solution { public: vector<int> twoSum(vector<int>& nums, int target) { vector<int> vect; for(int i = 0; i < nums.size(); ++i) { for (int j = i+1; j < nums.size(); ++j) { if (nums[i] + nums[j] == target) { vect.push_back(i); vect.push_back(j); } } } return vect; } };