题目：
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].
答案（常规解法）：
class Solution {
public:
vector<int> twoSum(vector<int>& nums, int target) {
vector<int> resArr;
for (int i = 0; i < nums.size(); i++) {
vector<int>::iterator res = find(nums.begin() + i + 1, nums.end(), target - nums[i] );
if (res != nums.end()) { /* find the number */
resArr.push_back(i);
for (int j = i + 1; j < nums.size(); j++) {
if (nums.at(j) == (*res)) {
resArr.push_back(j);
}
}
return resArr;
}
}
return resArr;
}
};
