1.两数之和.cpp

/*
 * @lc app=leetcode.cn id=1 lang=cpp
 *
 * [1] 两数之和
 */

// @lc code=start
class Solution {
   public:
    vector<int> twoSum(vector<int>& nums, int target) {
        // hash 法
        unordered_map<int, int> hash;
        for (int i = 0; i < nums.size(); i++) {
            auto it = hash.find(target - nums[i]);
            if (it != hash.end()) {
                return {it->second, i};
            }
            hash[nums[i]] = i;
        }
        return {};
    }
};
// @lc code=end