二分法查+范围内临近值查找

 1 uint16 FindPosition(uint8 arr[], uint16 length, uint8 target)
 2 {
 3     uint16 low = 0;
 4     uint16 high = length - 1;
 5     uint16 closest_position = 0xFFFF;
 6 
 7     if (target < arr[0] || target > arr[length - 1])
 8     {
 9         return 0xFFFF;  // target不在数组范围内
10     }
11 
12     while (low <= high)
13     {
14         uint16 mid = low + (high - low) / 2;
15 
16         if (arr[mid] == target)
17         {
18             return mid;
19         }
20         else if (arr[mid] < target)
21         {
22             closest_position = mid;  // 更新最接近且小于target的位置
23             low = mid + 1;
24         }
25         else
26         {
27             high = mid - 1;
28         }
29     }
30     
31     return closest_position;  // 返回最接近且小于target的位置
32 }

 1 int main(int argc, char *argv[])
 2 {
 3     uint8 arr[] = {1, 3, 5, 7, 10, 11, 13,17, 20, 23, 29,32,40,49};
 4     uint16 length = sizeof(arr) / sizeof(arr[0]);
 5     uint8 target = 14;
 6 
 7     uint16 position = FindPosition(arr, length, target);
 8 
 9     if (position != 0xFFFF)
10     {
11         printf("Closest position less than target found at position: %d\n", position);
12     }
13     else
14     {
15         printf("Target not in range\n");  //result:6
16     }
17     //system("pause");
18     return 0;
19 }