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.
Example:
Given nums = [2, 7, 11, 15], target = 9, Because nums[0] + nums[1] = 2 + 7 = 9, return [0, 1].
UPDATE (2016/2/13):
The return format had been changed to zero-based indices. Please read the above updated description carefully.
1 class Solution { 2 public: 3 vector<int> twoSum(vector<int>& nums, int target) { 4 vector<int> ret(2,-1); 5 6 unordered_map<int,int> myMap; 7 8 for(int i = 0 ; i < nums.size(); i++){ 9 if(myMap.find(target-nums[i]) == myMap.end()){ 10 myMap[nums[i]] = i; 11 }else{ 12 ret[0] = myMap[target-nums[i]]; 13 ret[1] = i; 14 return ret; 15 } 16 } 17 return ret; 18 } 19 };
原文：http://www.cnblogs.com/sankexin/p/5874617.html