1 /*************************************************************************
2 > File Name: 06_MinNumberInRotatedArray.c
3 > Author: Juntaran
4 > Mail: JuntaranMail@gmail.com
5 > Created Time: 2016年08月29日 星期一 20时14分22秒
6 ************************************************************************/
7
8 #include <stdio.h>
9 #include <stdlib.h>
10
11 // O(n)解法
12 int minNumberInRotatedArray1(int* rotatedArray, int length)
13 {
14 if (length <= 0)
15 return 0;
16
17 for (int i = 1; i < length; ++i)
18 {
19 if ( rotatedArray[i] < rotatedArray[i-1])
20 return rotatedArray[i];
21 }
22 return rotatedArray[0];
23 }
24
25 // O(log(n))解法
26 int minNumberInRotatedArray2(int* rotatedArray, int length)
27 {
28 if (length <= 0)
29 return 0;
30 if (length == 1)
31 return rotatedArray[0];
32 int left = 0;
33 int right = length - 1;
34 int middle = 0;
35
36 if (rotatedArray[left] < rotatedArray[right])
37 return rotatedArray[0];
38
39 while (rotatedArray[left] >= rotatedArray[right])
40 {
41 if (right - left == 1)
42 {
43 middle = right;
44 break;
45 }
46 middle = (left + right) / 2;
47
48 // 如果left、right、middle的值相同，只能顺序查找
49 if (rotatedArray[left]==rotatedArray[middle]
50 && rotatedArray[middle]==rotatedArray[right])
51 {
52 for (int i = left+1; i < right; ++i)
53 {
54 if (rotatedArray[i] < rotatedArray[i-1])
55 return rotatedArray[i];
56 }
57 return rotatedArray[left];
58 }
59
60 if (rotatedArray[middle] >= rotatedArray[left])
61 left = middle;
62 else if (rotatedArray[middle] <= rotatedArray[right])
63 right = middle;
64 }
65 return rotatedArray[middle];
66 }
67
68 int main()
69 {
70 int rotatedArray1[] = {1,1,1,1,1,1,1};
71 int rotatedArray2[] = {7,8,9,9,9,1,2};
72 int rotatedArray3[] = {8,1,2,3,4,5,6};
73 int rotatedArray4[] = {8,9,1,2,8,8,8,8,8,8};
74
75 int length1 = 7;
76 int length2 = 10;
77
78 int ret1, ret2;
79
80 ret1 = minNumberInRotatedArray1(rotatedArray1, length1);
81 ret2 = minNumberInRotatedArray2(rotatedArray1, length1);
82 printf("ret1 is %d, ret2 is %d\n", ret1, ret2);
83 ret1 = minNumberInRotatedArray1(rotatedArray2, length1);
84 ret2 = minNumberInRotatedArray2(rotatedArray2, length1);
85 printf("ret1 is %d, ret2 is %d\n", ret1, ret2);
86 ret1 = minNumberInRotatedArray1(rotatedArray3, length1);
87 ret2 = minNumberInRotatedArray2(rotatedArray3, length1);
88 printf("ret1 is %d, ret2 is %d\n", ret1, ret2);
89 ret1 = minNumberInRotatedArray1(rotatedArray4, length2);
90 ret2 = minNumberInRotatedArray2(rotatedArray4, length2);
91 printf("ret1 is %d, ret2 is %d\n", ret1, ret2);
92
93 return 0;
94 }
