1 class Sloution(object):
 2     @staticmethod  # two_sum方法不涉及对类属性的操作
 3     def two_sum(nums, target):
 4         num_store = dict()  # 存储key-value
 5         for i, num in enumerate(nums):
 6             if target - num in num_store:
 7                 return [i, num_store[target - num]]
 8             else:
 9                 num_store[num] = i  # 此处key是num,value是i,需要使用num定位其下标i
10 
11 if __name__ == ‘__main__‘:
12     the_target = 9
13     the_nums = [2, 7, 11, 15]
14     s = Sloution()
15     result = s.two_sum(the_nums, the_target)
16     print(result)  # [1, 0]

 1 #include "pch.h"
 2 #include <iostream>
 3 #include <vector>
 4 #include <unordered_map>
 5 using namespace std;
 6 
 7 class Sloution {
 8 public:
 9     vector<int> twoSum(vector<int> &nums, int target) {  // vector作为函数的参数或者返回值时需要注意:“&”绝对不能少
10         unordered_map<int, int> hash;  // unordered_map底层是哈希表，查找效率较高
11         vector<int> result;
12         int numsSize = nums.size();
13         for (int i = 0; i < numsSize; i++) {
14             int numToFind = target - nums[i];
15             if (hash.find(numToFind) != hash.end()) {  // 判断一个值是否在哈希表中的方法
16                 result.push_back(i);
17                 result.push_back(hash[numToFind]);
18                 return result;
19             }
20             else
21                 hash[nums[i]] = i;
22         }
23         //return result;  // leetcode上必须有这一行的返回结果
24     }
25 };
26 
27 int main() {
28     int theTarget = 9;
29     vector<int> theNums{2, 7, 11, 15};  // 初始化vector的方法
30     Sloution s;
31     for (auto res: s.twoSum(theNums, theTarget)) {  // 打印vector的方法
32         cout << res << " ";  // 1 0
33     }
34 }