{面试题8: 旋转数组的最小数字}

From 剑指Offer 何海涛 著

    int findMin(vector<int>& nums) {
        if(nums.empty()) {
            return 0;
        }
        int left = 0;
        int right = nums.size()-1;
        while(left < right && nums[left] >= nums[right]) {
            int middle = (left+right) >> 1;
　　　　　　　// 当三个值均相等时, 无法判断最小值位于哪个半区间, 只能顺序遍历
            if(nums[left] == nums[middle] && nums[left] == nums[right]) {
                int min = nums[left];
                for(int i=left+1; i<=right; i++) {
                    if(min > nums[i]) {
                        min = nums[i];
                    }
                }
                return min;
            }
            if(nums[middle] < nums[left]) {
                right = middle;
            } else {
                left = middle+1;
            }
        }
        return nums[left];
    }

测试集:

void test(const int array[], int length, int expected) {
    std::cout << std::boolalpha << (findMin(array, length) == expected) << std::endl;
}

int main(int argc, char* argv[]) {
    
    int array1[] = {3, 4, 5, 1, 2};
    int array2[] = {3, 4, 5, 1, 1, 2};
    int array3[] = {3, 4, 5, 1, 2, 2};
    int array4[] = {1, 0, 1, 1, 1,};
    int array5[] = {1, 2, 3, 4, 5};
    int array6[] = {2};
    int array7[] = {3, 1, 3};
    try {
        test(NULL, 5, 0);
    } catch (std::exception& e) {
        std::cout << "true" << std::endl;
    }

    try {
        test(array1, 0, 0);
    } catch (std::exception& e) {
        std::cout << "true" << std::endl;
    }

    test(array1, 5, 1);
    test(array2, 6, 1);
    test(array3, 6, 1);
    test(array4, 5, 0);
    test(array5, 5, 1);
    test(array6, 1, 2);
    test(array7, 3, 1);

    return 0;
}