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].需要了解一下unordered_map；class Solution {
public:
vector<int> twoSum(vector<int>& nums, int target) {
unordered_map<int,int>hash;
vector<int> result;
for(int i=0;i<nums.size();i++){
int numberToFind=target-nums[i];
if(hash.find(numberToFind)!=hash.end()){
result.push_back(hash[numberToFind]);
result.push_back(i);
return result;
}
hash[nums[i]]=i;
}
return result;
}
};