No1.Two Sum

/*
Two Sum Total Accepted: 114575 Total Submissions: 647786 My Submissions Question Solution
Given an array of integers, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.

You may assume that each input would have exactly one solution.

Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2
*/

/*以空间换时间*/

class Solution {
public:

vector<int> twoSum(vector<int>& nums, int target) {
vector <int> test(65536,-1);
vector<int> resultIndex;
int another;
for(int j =nums.size()-1;j>=0;j--)                      //O(N)
{
test.at(hash(nums.at(j))) = j;
}
for(int i=0;i<nums.size();i++)                          //O(N)
{
another = target - nums.at(i);
int maybeIndex =test.at(hash(another));
if(maybeIndex >=0 && maybeIndex!=i)
{
resultIndex.push_back(maybeIndex+1);
resultIndex.push_back(i+1);
break;
}
}
if (resultIndex[0]>resultIndex[1])
{
resultIndex[0] = resultIndex[0] ^ resultIndex[1];
resultIndex[1] = resultIndex[0] ^ resultIndex[1];
resultIndex[0] = resultIndex[0] ^ resultIndex[1];
}
return resultIndex;

}
int hash(int input)
{
if(input<0)
{
return 32767-input;
}else
{
return input;
}
}

};