add 001-Two Sum

001-Two Sum/README.md

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+LeetCode第一个题
+
+# C++
+刚开始用暴力匹配，后来看了答案恍然大悟，hash会快很多

001-Two Sum/solution.h

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+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+        map<int, int>mp;
+        vector<int>ans;
+        int len = nums.size();
+        for(int i = 0; i < len; i++){
+            if( mp.find(target - nums[i]) != mp.end()){
+                ans.push_back(mp[target - nums[i]]);
+                ans.push_back(i);
+                return ans;
+            }
+            mp[nums[i]] = i;  
+        }     
+    }
+};