旋转数组的最小值

题目描述

把一个数组最开始的若干个元素搬到数组的末尾，我们称之为数组的旋转。输入一个非递减序列的一个旋转，输出旋转数组的最小元素。例如数组{3,4,5,1,2}为{1,2,3,4,5}的一个旋转，该数组的最小值为1。

 1 class Solution {
 2 public:
 3     int minNumberInRotateArray(vector<int> rotateArray) {
 4         if(rotateArray.empty())
 5             return 0;
 6         int index1 = 0;
 7         int index2 = rotateArray.size()-1;
 8         int indexMid = index1;
 9         while(rotateArray[index1] >= rotateArray[index2]){
10             // quit condition
11             if(index2 - index1 == 1){
12                 indexMid = index2;
13                 break;
14             }
15             indexMid = (index1 + index2) / 2;
16             //the three numbers are equal
17             if(rotateArray[index1] == rotateArray[index2]
18               && rotateArray[indexMid] == rotateArray[index1]){
19                 return MinInOrder(rotateArray,index1,index2);
20             }
21             //no equal
22             if(rotateArray[indexMid] >= rotateArray[index1]){
23                 index1 = indexMid;
24             }
25             else if(rotateArray[indexMid] <= rotateArray[index2]){
26                 index2 = indexMid;
27             }
28         }
29         return rotateArray[indexMid];
30     }
31
32     int MinInOrder(vector<int> rotateArray,int index1,int index2){
33         int result = rotateArray[index1];
34         for(int i=index1+1;i<=index2;i++){
35             if(result > rotateArray[i])
36                 result = rotateArray[i];
37         }
38         return result;
39     }
40 };