leetcode Two Sum

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].


class Solution {
public:
    vector<int> twoSum(vector<int>& numbers, int target) {
        unordered_map<int, int> hash;
        vector<int> result;
        for (int i = 0; i < numbers.size(); i++) {
            int numberToFind = target - numbers[i];

            //if numberToFind is found in map, return them
            if (hash.find(numberToFind) != hash.end()) {
                result.push_back(hash[numberToFind]);
                result.push_back(i);            
                return result;
            }

            //number was not found. Put it in the map.
            hash[numbers[i]] = i;
        }
        return result;
    }
};

呼呼呼山(http://code4fun.me)
1 May 2017 7:51 PM