1 /********************************************************************
2 created: 2014/01/05
3 created: 22:01
4 file base: main
5 file ext: cpp
6 author: Justme0 (http://blog.csdn.net/Justme0)
7
8 purpose: 求两个等长的有序序列的中位数，时间复杂度O(log(n))
9 *********************************************************************/
10
11 #define _CRT_SECURE_NO_WARNINGS
12 #include <iostream>
13 #include <vector>
14 #include <cassert>
15 #include <algorithm>
16 using namespace std;
17
18 template <class Iterator>
19 Iterator search_middle(Iterator begin1, Iterator end1, Iterator begin2) {
20 while (begin1 + 1 != end1) {
21 int len = end1 - begin1;
22 int m = (len - 1) / 2; // m 是中位数的下标
23 bool is_odd = (len % 2 == 1);
24
25 if (begin1[m] < begin2[m]) {
26 if (is_odd) {
27 begin1 += m;
28 } else {
29 begin1 += m + 1;
30 }
31 } else if (begin2[m] < begin1[m]) {
32 if (is_odd) {
33 begin2 += m;
34 end1 -= m;
35 } else {
36 begin2 += m + 1;
37 end1 -= m + 1;
38 }
39 } else {
40 return begin1 + m;
41 }
42 }
43
44 return *begin1 < *begin2 ? begin1 : begin2;
45 }
46
47 void input(vector<int> &v, int len) {
48 for (int i = 0; i < len; ++i) {
49 int elem;
50 cin >> elem;
51 v.push_back(elem);
52 }
53 }
54
55 void output(vector<int> &v) {
56 for (vector<int>::iterator it = v.begin(); it != v.end(); ++it) {
57 cout << *it << " ";
58 }
59 cout << endl;
60 }
61
62 int main(int argc, char **argv) {
63 freopen("cin.txt", "r", stdin);
64
65 int len;
66 while (cin >> len) {
67 vector<int> v1, v2;
68 input(v1, len);
69 input(v2, len);
70
71 vector<int> v3(v1.size() * 2);
72 merge(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin());
73 int b = v3[(v3.size() - 1) / 2];
74
75 int a = *search_middle(v1.begin(), v1.end(), v2.begin());
76 assert(a == b);
77 cout << a << " " << b << endl;
78 if(a != b) {
79 output(v3);
80 cout << "a=" << a << endl;
81 cout << "b=" << b << endl;
82 }
83 }
84
85 return 0;
86 }
87
88 /* cin.txt
89 1
90 1
91 0
92
93 1
94 -3
95 3
96
97 2
98 1 2
99 2 3
100
101 3
102 0 5 6
103 2 2 2
104
105 4
106 1 2 3 4
107 6 7 8 9
108
109 4
110 1 2 6 7
111 3 4 5 6
112
113 5
114 12 22 222 333 3333
115 10 13 44 55 66
116
117 10
118 3 3 22 34 44 333 2222 11111 11112 11113
119 -5 -4 0 1 444 4444 44444 44445 444444 444445
120 */
