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Program.cs
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Program.cs
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//思路为使用left和right两个指针从数组两边向中间扫描。
//创建left和right指针分别指向数组的头尾。创建res用于记录结果,初始值设为-1。
//在left <= right的条件下遍历数组,一旦发现left或者right所指向元素等于target,就将res设为相应的left或者right,并停止遍历。
//如果target与left指向元素差的绝对值大于target于right指向元素差的绝对值(找出谁离target更近),则让right向左移动。否则让left向右移动。
using System;
namespace SearchInRotatedSortedArray
{
class Program
{
static void Main(string[] args)
{
int[] nums = {4, 5, 6, 7, 0, 1, 2};
int target = 4;
Console.WriteLine(Search1(nums, target));
}
static int Search1(int[] nums, int target)
{
int li = 0, hi = nums.Length - 1;
while (li <= hi)
{
int mid = li + (hi - li) / 2;
if (nums[mid] == target)
return mid;
if (nums[mid] < nums[hi])
{
if (nums[mid] < target && target <= nums[hi])
li = mid + 1;
else
hi = mid - 1;
}
else
{
if (nums[li] <= target && target < nums[mid])
hi = mid - 1;
else
li = mid + 1;
}
}
return -1;
}
static int Search2(int[] nums, int target)
{
int left = 0;
int right = nums.Length - 1;
int res = -1;
while (left <= right)
{
if (nums[left] == target)
{
res = left;
break;
}
else if (nums[right] == target)
{
res = right;
break;
}
if (Math.Abs(target - nums[left]) > Math.Abs(target - nums[right]))
right--;
else
left++;
}
return res;
}
}
}