C++黑马程序员——P251-254. 常用排序算法 sort，random_shuffle，merge，reverse

• P251. 常用排序算法——sort
• P252. ...——random_shuffle
• P253. ...——merge
• P254. ...——reverse
• P251. sort

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 #include <functional>    //用greater
 5 using namespace std;
 6 
 7 //排序算法 sort
 8 void test01()
 9 {
10     vector<int>v;
11     v.push_back(20);
12     v.push_back(10);
13     v.push_back(50);
14     v.push_back(40);
15     v.push_back(30);
16 
17     //利用sort升序
18  sort(v.begin(), v.end());
19     //打印输出
20     for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
21     {
22         cout << *it << " ";
23     }
24     cout << endl;
25 
26     //降序
27     sort(v.begin(), v.end(), greater<int>());
28     for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
29     {
30         cout << *it << " ";
31     }
32     cout << endl;
33 }
34 
35 int main()
36 {
37     test01();
38     return 0;
39 }

运行结果：

• P252. random_shuffle

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 #include <ctime>    //为了添加随机数种子的
 5 using namespace std;
 6 
 8 void test01()
 9 {
10     srand((unsigned int)time(NULL));    //添加随机数种子，不然每次用random_shuffle打乱的顺序都是一样的
11 
12     vector<int>v;
13     for (int i = 0; i < 10; i++)
14     {
15         v.push_back(i);
16     }
17 
18     //利用洗牌算法 打乱顺序
19  random_shuffle(v.begin(), v.end());
20 
21     //打印输出
22     for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
23     {
24         cout << *it << " ";
25     }
26     cout << endl;
27 
28 }
29 
30 int main()
31 {
32     test01();
33     return 0;
34 }

运行结果：

使用时记得添加随机数种子

• P253. merge

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 using namespace std;
 5 
 6 //merge
 7 void test01()
 8 {
 9     vector<int>v1;
10     vector<int>v2;
11 
12     //原容器需要是有序序列
13     for (int i = 0; i < 10; i++)
14     {
15         v1.push_back(i);
16         v2.push_back(i + 1);
17     }
18 
19     //准备一个目标容器
20     vector<int>vTarget;
21     //提前给目标容器分配空间(否则运行时会报错)
22     vTarget.resize(v1.size() + v2.size());
23 
24  merge(v1.begin(), v1.end(), v2.begin(), v2.end(), vTarget.begin());
25 
26     for (vector<int>::iterator it = vTarget.begin(); it != vTarget.end(); it++)
27     {
28         cout << *it << " ";
29     }
30     cout << endl;
31 }
32 
33 int main()
34 {
35     test01();
36     return 0;
37 }

运行结果：

• P254. reverse

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 using namespace std;
 5 
 6 //reverse
 7 void test01()
 8 {
 9     vector<int>v;
10     v.push_back(1);
11     v.push_back(3);
12     v.push_back(5);
13     v.push_back(2);
14     v.push_back(4);
15     
16     cout << "反转前：" << endl;
17     for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
18     {
19         cout << *it << " ";
20     }
21     cout << endl;
22 
23  reverse(v.begin(), v.end());
24     cout << "反转后：" << endl;
25     for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
26     {
27         cout << *it << " ";
28     }
29     cout << endl;
30 }
31 
32 int main()
33 {
34     test01();
35     return 0;
36 }

运行结果：

(〃＞＿＜;〃)(〃＞＿＜;〃)(〃＞＿＜;〃)