add 1 exercises

data/3.算法高阶/1.leetcode/0_两数之和/solution.cpp

 #include <unordered_map>
+#include <vector>
+#include <iostream>
+using namespace std;
 class Solution
 {
 public:
@@ -21,3 +24,17 @@ public:
 		return r;
 	}
 };
+
+int main()
+{
+	Solution test;
+	int arr[] = {3, 2, 4};
+	vector<int> ret;
+	vector<int> vec(arr, arr + 4);
+	ret = test.twoSum(vec, 6);
+	for (auto i = ret.begin(); i != ret.end(); i++)
+	{
+		cout << *i << ' ';
+	}
+	return 0;
+}

data/3.算法高阶/1.leetcode/0_两数之和/solution.md

+# 两数之和
+以下错误的选项是？
+## aop
+### before
+```cpp
+#include <unordered_map>
+#include <vector>
+#include <iostream>
+#include <map>
+using namespace std;
+```
+### after
+```cpp
+int main()
+{
+	Solution test;
+	int arr[] = {3,2,4};
+	vector<int> ret;
+	vector<int> vec(arr, arr+4);
+	ret = test.twoSum(vec, 6);
+	for (auto i = ret.begin(); i != ret.end(); i++)
+	{
+		cout << *i << ' ';
+	}
+	return 0;
+}
+```
+
+## 答案
+```cpp
+class Solution
+{
+public:
+    vector<int> twoSum(vector<int> &nums, int target)
+    {
+        vector<int> vec;
+        map<int, int> dic; 
+        for (int i = 0; i < nums.size(); ++i)
+        {
+            dic[nums[i]] = i;
+        }
+        for (int i = 0; i < nums.size(); ++i)
+        {
+            if (dic.count(target - nums[i]) != 0 && dic[target - nums[i]] != i)
+            {
+                vec.push_back(i);
+                vec.push_back(dic[target]);
+                break;
+            }
+        }
+        return vec;
+    }
+};
+```
+## 选项
+
+### A
+```cpp
+class Solution
+{
+public:
+    vector<int> twoSum(vector<int> &nums, int target)
+    {
+        vector<int> a;
+        map<int, int> map;
+        for (int i = 0; i < nums.size(); i++)
+        {
+            map[nums[i]] = i;
+        }
+        for (int j = 0; j < nums.size(); j++)
+        {
+            if (map.count(target - nums[j]) == 1 && map[target - nums[j]] != j)
+            {
+                a.push_back(j);
+                a.push_back(map[target - nums[j]]);
+                return a;
+            }
+        }
+        return a;
+    }
+};
+```
+
+### B
+```cpp
+class Solution
+{
+public:
+    vector<int> twoSum(vector<int> &nums, int target)
+    {
+        vector<int> a;
+        map<int, int> map;
+        for (int i = 0; i < nums.size(); i++)
+        {
+            if (map.find(target - nums[i]) != map.end())
+            {
+                a.push_back(map[target - nums[i]]);
+                a.push_back(i);
+                return a;
+            }
+            else
+            {
+                map[nums[i]] = i;
+            }
+        }
+        return a;
+    }
+};
+```
+
+### C
+```cpp
+class Solution
+{
+public:
+    vector<int> twoSum(vector<int> &nums, int target)
+    {
+        vector<int> a;
+        for (int i = 0; i < nums.size(); i++)
+        {
+            for (int j = i + 1; j < nums.size(); j++)
+            {
+                if (nums[i] + nums[j] == target)
+                {
+                    a.push_back(i);
+                    a.push_back(j);
+                    return a;
+                }
+            }
+        }
+    }
+};
+```