STL中的nth_element()方法的使用

 1 #include <iostream>
 2 
 3 #include <algorithm>
 4 
 5 #include <functional>
 6 
 7 #include <vector>
 8 
 9 using namespace std;
10 
11 
12 
13 int main()
14 
15 {
16 
17     const int VECTOR_SIZE = 50 ;
18 
19 
20 
21     vector<int> Numbers(VECTOR_SIZE) ;
22 
23 
24 
25     vector<int>::iterator start, end, it ;
26 
27 
28 
29     // Initialize vector Numbers
30 
31     for(int i=0;i<50;++i){
32 
33              Numbers[i]=i;
34 
35     }
36 
37 /*由于赋值时是有序的，下面random_shuffle()方法将这些数据的顺序打乱*/
38 
39     random_shuffle(Numbers.begin(),Numbers.end());
40 
41     
42 
43 // location of first element of Numbers
44 
45     start = Numbers.begin() ; 
46 
47 
48 
49  // one past the location last element of Numbers
50 
51     end = Numbers.end() ;     
52 
53 
54 
55     cout << "Before calling nth_element/n" << endl ;
56 
57 
58 
59   // print content of Numbers
60 
61     cout << "Numbers { " ;
62 
63     for(it = start; it != end; it++)
64 
65         cout << *it << " " ;
66 
67     cout << " }/n" << endl ;
68 
69 
70 
71   /* 
72 
73     * partition the elements by the 8th element，
74 
75   *（notice that 0th is the first element）
76 
77   */ 
78 
79     nth_element(start, start+8, end) ;
80 
81 
82 
83     cout << "After calling nth_element/n" << endl ;
84 
85 
86 
87     cout << "Numbers { " ;
88 
89     for(it = start; it != end; it++)
90 
91         cout << *it << " " ;
92 
93     cout << " }/n" << endl ;
94 
95     system("pause");
96 
97 }