Given an array of integers, find two numbers such that they add up to a specific target number.
The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are NOT zero-based.
Notice
You may assume that each input would have exactly one solution
Example
numbers=[2, 7, 11, 15], target=9
return [1, 2]
Challenge
Either of the following solutions are acceptable:
- O(n) Space, O(nlogn) Time
- O(n) Space, O(n) Time
LeetCode上的原题，请参见我之前的博客Two Sum。
class Solution { public: /* * @param numbers : An array of Integer * @param target : target = numbers[index1] + numbers[index2] * @return : [index1+1, index2+1] (index1 < index2) */ vector<int> twoSum(vector<int> &nums, int target) { unordered_map<int, int> m; for (int i = 0; i < nums.size(); ++i) m[nums[i]] = i; for (int i = 0; i < nums.size(); ++i) { int t = target - nums[i]; if (m.count(t) && m[t] != i) { return {i + 1, m[t] + 1}; } } return {}; } };
本文转自博客园Grandyang的博客，原文链接：两数之和[LintCode] Two Sum ，如需转载请自行联系原博主。
