【剑指offer】面试题57：和为s的两个数字

方法一：哈希表查找

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        unordered_map<int,int> record;
        vector<int> result;
        for( int i = 0; i < nums.size(); i++ )
        {
             record[ nums[i] ] = i;
        }
        for(int i = 0; i <nums.size(); i++)
        {
            if( record.find(target - nums[i]) != record.end() )
            {
                result.push_back(nums[i]);
                result.push_back( nums[ record[ target - nums[i] ]] );
                return result;
            }
        }
        throw invalid_argument("no solution");
    }
};