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。

 

class Solution {
public:
    int minNumberInRotateArray(vector<int> rotateArray) {
        if(rotateArray.empty())
            return 0;
        int index1 = 0;
        int index2 = rotateArray.size()-1;
        int indexMid = index1;
        while(rotateArray[index1] >= rotateArray[index2]){
            // quit condition
            if(index2 - index1 == 1){
                indexMid = index2;
                break;
            }
            indexMid = (index1 + index2) / 2;
            //the three numbers are equal
            if(rotateArray[index1] == rotateArray[index2] 
              && rotateArray[indexMid] == rotateArray[index1]){
                return MinInOrder(rotateArray,index1,index2);
            }
            //no equal
            if(rotateArray[indexMid] >= rotateArray[index1]){
                index1 = indexMid;
            }
            else if(rotateArray[indexMid] <= rotateArray[index2]){
                index2 = indexMid;
            }
        }
        return rotateArray[indexMid];
    }
    
    int MinInOrder(vector<int> rotateArray,int index1,int index2){
        int result = rotateArray[index1];
        for(int i=index1+1;i<=index2;i++){
            if(result > rotateArray[i])
                result = rotateArray[i];
        }
        return result;
    }
};