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problems/0000.TwoSum.md

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+## 题目地址 
+https://leetcode-cn.com/problems/two-sum/ 
+
+## 思路 
+
+## 一般解法 
+
+代码：
+
+```C++
+```
+
+## 优化解法 
+
+```C++
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+        for (int i = 0; i < nums.size(); i ++) {
+            for (int j = i + 1; j < nums.size(); j++) {
+                if (nums[i] + nums[j] == target) {
+                    return {i, j};
+                }
+            }
+        }
+        return {};
+    }
+};
+
+```
+
+```
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+        std::map <int,int> map;
+        for(int i = 0; i < nums.size(); i++) {
+            auto iter = map.find(target - nums[i]);
+            if(iter != map.end()) {
+                return {iter->second,i};
+            }
+            map[nums[i]] = i;
+        }
+        return {};
+    }
+};
+```
+
+```
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+        std::unordered_map <int,int> map;
+        for(int i = 0; i < nums.size(); i++) {
+            auto iter = map.find(target - nums[i]);
+            if(iter != map.end()) {
+                return {iter->second, i};
+                break;
+            }
+            map.emplace(nums[i], i);
+        }
+        return {};
+    }
+};
+```
+## 代码
+
+```C++
+
+```