我正在尝试解决模板2中的二进制搜索问题..在旋转排序数组中查找最小值。问题如下:
假设按升序排序的长度为n的数组在1到n次之间旋转。例如,数组nums=[0,1,2,4,5,6,7]可能会变成:
[4,5,6,7,0,1,2] if it was rotated 4 times.
[0,1,2,4,5,6,7] if it was rotated 7 times.
请注意,将数组[a[0]、a[1]、a[2]、…、a[n-1]]旋转1次会导致数组[a[n-1]、a[0]、a[1]、a[2]、…、a[n-2]]。
给定已排序的旋转数组nums,返回此数组的最小元素。
例1:
Input: nums = [3,4,5,1,2]
Output: 1
Explanation: The original array was [1,2,3,4,5] rotated 3 times.
例2:
Input: nums = [4,5,6,7,0,1,2]
Output: 0
Explanation: The original array was [0,1,2,4,5,6,7] and it was rotated 4 times.
例3:
Input: nums = [11,13,15,17]
Output: 11
Explanation: The original array was [11,13,15,17] and it was rotated 4 times.
约束条件:
n == nums.length
1 <= n <= 5000
-5000 <= nums[i] <= 5000
All the integers of nums are unique.
nums is sorted and rotated between 1 and n times.
我的解决方案代码如下:
public int findMin(int[] nums) {
if(nums == null || nums.length == 0) {
return -1;
}
if(nums.length == 1) return nums[0];
if(nums.length == 2) {
return (nums[0] > nums[1])? nums[1]:nums[0];
}
int left = 0;
int right = nums.length;
while(left < right) {
int mid = left + (right - left)/2;
// [3,4,5,1,2]
if(nums[mid] > nums[mid + 1]) {
return nums[mid + 1];
} else if(nums[mid] < nums[mid + 1]) {
right = mid;
}
}
if(left != nums.length) {
return nums[left];
}
return -1;
}
我的代码适用于以下示例集:
nums = [3,4,5,1,2]
nums = [4,5,6,7,0,1,2]
nums = [11,13,15,17]
nuts = [4,5,6,7,0,1,2]
但是当我试图提交代码时,我得到的错误如下:
Runtime Error Message:
java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1
at line 16, Solution.findMin
at line 54, __DriverSolution__.__helper__
at line 84, __Driver__.main
Last executed input:
[1]
有人能指出我的编码逻辑中的缺陷吗?
编辑:我在解决方案中添加了两个case(对于nums.length==1或2)。
if(nums.length == 1) return nums[0];
if(nums.length == 2) {
return (nums[0] > nums[1])? nums[1]:nums[0];
}
但是当nums=[2,3,4,5,1]的时候,我还是得到了一个错误,也就是说,我得到的结果值是2,但是原来的答案是1。
1条答案
按热度按时间kqqjbcuj1#
臭虫
你阵型的中部
应该是第三个元素
mid=3
中间值计算错误。例如,在您的第一次迭代中
left=0
以及right=5
所以下面的计算结果是原因
因为将结果赋给整数,所以小数部分将丢失。结果不是2,5,2
汇总
下面的函数将对结果进行四舍五入,以便计算正确的中值
使用调用函数
其他案例
你必须考虑长度为1,长度为2的情况