剑指Offer06 旋转数组的最小值

/*************************************************************************
    > File Name: 06_MinNumberInRotatedArray.c
    > Author: Juntaran
    > Mail: JuntaranMail@gmail.com
    > Created Time: 2016年08月29日 星期一 20时14分22秒
 ************************************************************************/

#include <stdio.h>
#include <stdlib.h>

// O(n)解法
int minNumberInRotatedArray1(int* rotatedArray, int length)
{
    if (length <= 0)
        return 0;
    
    for (int i = 1; i < length; ++i)
    {
        if ( rotatedArray[i] < rotatedArray[i-1])
            return rotatedArray[i];
    }
    return rotatedArray[0];
}

// O(log(n))解法
int minNumberInRotatedArray2(int* rotatedArray, int length)
{
    if (length <= 0)
        return 0;
    if (length == 1)
        return rotatedArray[0];
    int left  = 0;
    int right = length - 1;
    int middle = 0;
    
    if (rotatedArray[left] < rotatedArray[right])
        return rotatedArray[0];
    
    while (rotatedArray[left] >= rotatedArray[right])
    {
        if (right - left == 1)
        {
            middle = right;
            break;
        }
        middle = (left + right) / 2;
        
        // 如果left、right、middle的值相同，只能顺序查找
        if (rotatedArray[left]==rotatedArray[middle] 
        && rotatedArray[middle]==rotatedArray[right])
        {
            for (int i = left+1; i < right; ++i)
            {
                if (rotatedArray[i] < rotatedArray[i-1])
                    return rotatedArray[i];
            }
            return rotatedArray[left];
        }
        
        if (rotatedArray[middle] >= rotatedArray[left])
            left = middle;
        else if (rotatedArray[middle] <= rotatedArray[right])
            right = middle;
    }
    return rotatedArray[middle];
}

int main()
{
    int rotatedArray1[] = {1,1,1,1,1,1,1};
    int rotatedArray2[] = {7,8,9,9,9,1,2};
    int rotatedArray3[] = {8,1,2,3,4,5,6};
    int rotatedArray4[] = {8,9,1,2,8,8,8,8,8,8};
    
    int length1 = 7;
    int length2 = 10;
    
    int ret1, ret2;
    
    ret1 = minNumberInRotatedArray1(rotatedArray1, length1);
    ret2 = minNumberInRotatedArray2(rotatedArray1, length1);
    printf("ret1 is %d, ret2 is %d
", ret1, ret2);
    ret1 = minNumberInRotatedArray1(rotatedArray2, length1);
    ret2 = minNumberInRotatedArray2(rotatedArray2, length1);
    printf("ret1 is %d, ret2 is %d
", ret1, ret2);
    ret1 = minNumberInRotatedArray1(rotatedArray3, length1);
    ret2 = minNumberInRotatedArray2(rotatedArray3, length1);
    printf("ret1 is %d, ret2 is %d
", ret1, ret2);
    ret1 = minNumberInRotatedArray1(rotatedArray4, length2);
    ret2 = minNumberInRotatedArray2(rotatedArray4, length2);
    printf("ret1 is %d, ret2 is %d
", ret1, ret2);
    
    return 0;
}