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].
1 class Solution { 2 public: 3 vector<int> twoSum(vector<int>& nums, int target) { 4 5 unordered_map<int, int> hash_map; 6 vector<int> tmp; 7 8 for (int i = 0; i < nums.size(); ++i) 9 { 10 hash_map[nums[i]] = i; 11 } 12 13 for (int i = 0; i < nums.size(); ++i) 14 { 15 const int diff = target - nums[i]; 16 if (hash_map.find(diff) != hash_map.end() && hash_map[diff] != i) 17 { 18 tmp.push_back(i); 19 tmp.push_back(hash_map[diff]); 20 break; 21 } 22 } 23 24 return tmp; 25 } 26 };
原文：http://www.cnblogs.com/lijiatu/p/5366181.html