[LeetCode] Two Sum

解法1：

class Solution{
public:
    vector<int>twoSum(vector<int> &numbers,int target){
        vector<int> a = numbers;
        vector<int> result;
        sort(a.begin(),a.end());
        int sum = 0,i = 0,j = (int)a.size() - 1;
        while(i <j){
            sum = a[i] + a[j];
            if(sum < target)
                i ++;
            else if(sum > target)
                j --;
            else
                break;
        }
        for(int m = 0;m < numbers.size();m ++){
            if(a[i] == numbers[m]){
                i = m + 1;
                break;
            }
        }
        for(int n = numbers.size() - 1;n >= 0;n --){
            if(a[j] == numbers[n]){
                j = n + 1;
                break;
            }
        }
        result.push_back(i < j? i:j);
        result.push_back(i > j? i:j);
        return result;
    }
};

解法2：

class Solution{
public:
    vector<int> twoSum(vector<int> &numbers,int target){
        vector<int> result;
        map<int,int> m;
        for(int i = 0;i < numbers.size();i ++){
            if(m[target - numbers[i]] > 0){
                result.push_back(m[target - numbers[i]]);
                result.push_back(i + 1);
            }
            else
                m[numbers[i]] = i + 1;
        }
        return result;
    }
};