00018

力扣 1 两数之和
使用哈希表

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

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        f = set()
        for i ,num in enumerate(nums):
            item = target - num
            if item in f:
                return [nums.index(item), i]
            f.add( num)