题目链接

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.
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.

解答思路

TODO （稍后补充）

解答代码

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        unordered_map<int, int> map;
        vector<int> output;
        for(int i=0;i<nums.size();i++) {
            if(map.find(nums[i])!=map.end()) {
                output.push_back(map[nums[i]]);
                output.push_back(i);
                return output;
            }
            map[target - nums[i]] = i;
        }
        return output;
    }
};