feat: selection sort, merge sort in cpp (doocs#557)

Co-authored-by: willrlzhang <willrlzhang@tencent.com>
Co-authored-by: MaoLongLong <382084620@qq.com>

Author: 3 people

basic/sorting/MergeSort/Main.cpp

@@ -0,0 +1,74 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+void printvec( const vector<int> &vec, const string &strbegin = "", const string &strend = "" )
+{
+	cout << strbegin << endl;
+	for ( auto val : vec )
+	{
+		cout << val << "\t";
+	}
+
+	cout << endl;
+	cout << strend << endl;
+}
+
+
+void mergesort( vector<int> & vec, int left, int right )
+{
+	if ( left >= right )
+	{
+		return;
+	}
+
+	int mid = left + (right - left) / 2;
+	mergesort( vec, left, mid );
+	mergesort( vec, mid + 1, right );
+
+	int i = left;
+	int j = mid + 1;
+	int k = 0;
+	vector<int>	vecTmp;
+	while ( i <= mid && j <= right )
+	{
+		if ( vec[i] < vec[j] )
+		{
+			vecTmp.push_back( vec[i] );
+			i++;
+		}else  {
+			vecTmp.push_back( vec[j] );
+			j++;
+		}
+	}
+
+	while ( i <= mid )
+	{
+		vecTmp.push_back( vec[i] );
+		i++;
+	}
+
+	while ( j <= right )
+	{
+		vecTmp.push_back( vec[j] );
+		j++;
+	}
+
+	for ( int i = left; i <= right; i++ )
+	{
+		vec[i] = vecTmp[i - left];
+	}
+
+	return;
+}
+
+
+int main( void )
+{
+	vector<int> vec = { 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 };
+	printvec( vec );
+	mergesort( vec, 0, vec.size() - 1 );
+	printvec( vec, "after insert sort" );
+	return(0);
+}

basic/sorting/MergeSort/README.md

@@ -101,7 +101,7 @@ def merge_sort(nums, left, right):
     while j <= right:
         tmp.append(nums[j])
         j += 1
-    
+
     j = 0
     for i in range(left, right + 1):
         nums[i] = tmp[j]
@@ -119,7 +119,7 @@ import java.util.Scanner;
 
 public class Main {
     private static int[] tmp = new int[100010];
-    
+
     public static void main(String[] args) {
         Scanner sc = new Scanner(System.in);
         int n = sc.nextInt();
@@ -132,7 +132,7 @@ public class Main {
             System.out.printf("%d ", nums[i]);
         }
     }
-    
+
     public static void mergeSort(int[] nums, int left, int right) {
         if (left >= right) {
             return;
@@ -179,7 +179,7 @@ function mergeSort(nums, left, right) {
     if (left >= right) {
         return;
     }
-    
+
     const mid = (left + right) >> 1;
     mergeSort(nums, left, mid);
     mergeSort(nums, mid + 1, right);
@@ -272,5 +272,83 @@ func main() {
 }
 ```
 
+### **C++**
+
+```cpp
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+void printvec( const vector<int> &vec, const string &strbegin = "", const string &strend = "" )
+{
+    cout << strbegin << endl;
+    for ( auto val : vec )
+    {
+        cout << val << "\t";
+    }
+
+    cout << endl;
+    cout << strend << endl;
+}
+
+
+void mergesort( vector<int> & vec, int left, int right )
+{
+    if ( left >= right )
+    {
+        return;
+    }
+
+    int mid = left + (right - left) / 2;
+    mergesort( vec, left, mid );
+    mergesort( vec, mid + 1, right );
+
+    int i = left;
+    int j = mid + 1;
+    int k = 0;
+    vector<int>	vecTmp;
+    while ( i <= mid && j <= right )
+    {
+        if ( vec[i] < vec[j] )
+        {
+            vecTmp.push_back( vec[i] );
+            i++;
+        }else  {
+            vecTmp.push_back( vec[j] );
+            j++;
+        }
+    }
+
+    while ( i <= mid )
+    {
+        vecTmp.push_back( vec[i] );
+        i++;
+    }
+
+    while ( j <= right )
+    {
+        vecTmp.push_back( vec[j] );
+        j++;
+    }
+
+    for ( int i = left; i <= right; i++ )
+    {
+        vec[i] = vecTmp[i - left];
+    }
+
+    return;
+}
+
+
+int main( void )
+{
+    vector<int> vec = { 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 };
+    printvec( vec );
+    mergesort( vec, 0, vec.size() - 1 );
+    printvec( vec, "after insert sort" );
+    return(0);
+}
+```
 
 <!-- tabs:end -->

basic/sorting/SelectionSort/README.md

@@ -90,6 +90,55 @@ func main() {
 }
 ```
 
+### **C++**
+
+```cpp
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+void printvec( const vector<int> &vec, const string &strbegin = "", const string &strend = "" )
+{
+    cout << strbegin << endl;
+    for ( auto val : vec )
+    {
+        cout << val << "\t";
+    }
+
+    cout << endl;
+    cout << strend << endl;
+}
+
+
+void selectsort( vector<int> & vec )
+{
+    for ( int i = 0; i < vec.size() - 1; i++ )
+    {
+        int minidx = i;
+        for ( int j = i + 1; j < vec.size(); j++ )
+        {
+            if ( vec[minidx] > vec[j] )
+            {
+                minidx = j;
+            }
+        }
+
+        swap( vec[i], vec[minidx] );
+    }
+}
+
+
+int main( void )
+{
+    vector<int> vec = { 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 };
+    printvec( vec );
+    selectsort( vec );
+    printvec( vec, "after insert sort" );
+    return(0);
+}
+```
+
 <!-- tabs:end -->
 
 ## 算法分析

basic/sorting/SelectionSort/SelectionSort.cpp

@@ -0,0 +1,44 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+void printvec( const vector<int> &vec, const string &strbegin = "", const string &strend = "" )
+{
+	cout << strbegin << endl;
+	for ( auto val : vec )
+	{
+		cout << val << "\t";
+	}
+
+	cout << endl;
+	cout << strend << endl;
+}
+
+
+void selectsort( vector<int> & vec )
+{
+	for ( int i = 0; i < vec.size() - 1; i++ )
+	{
+		int minidx = i;
+		for ( int j = i + 1; j < vec.size(); j++ )
+		{
+			if ( vec[minidx] > vec[j] )
+			{
+				minidx = j;
+			}
+		}
+
+		swap( vec[i], vec[minidx] );
+	}
+}
+
+
+int main( void )
+{
+	vector<int> vec = { 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 };
+	printvec( vec );
+	selectsort( vec );
+	printvec( vec, "after insert sort" );
+	return(0);
+}